diff --git a/modules/payment/commerce_payment.info.yml b/modules/payment/commerce_payment.info.yml
new file mode 100644
index 0000000..4bb9b72
--- /dev/null
+++ b/modules/payment/commerce_payment.info.yml
@@ -0,0 +1,7 @@
+name: Commerce Payment
+type: module
+description: 'Provides payment functionality.'
+package: Commerce
+core: 8.x
+dependencies:
+  - commerce_order
diff --git a/modules/payment/commerce_payment.links.action.yml b/modules/payment/commerce_payment.links.action.yml
new file mode 100644
index 0000000..09c4a7a
--- /dev/null
+++ b/modules/payment/commerce_payment.links.action.yml
@@ -0,0 +1,5 @@
+entity.commerce_payment_gateway.add_form:
+  route_name: entity.commerce_payment_gateway.add_form
+  title: 'Add payment gateway'
+  appears_on:
+    - entity.commerce_payment_gateway.collection
diff --git a/modules/payment/commerce_payment.links.menu.yml b/modules/payment/commerce_payment.links.menu.yml
new file mode 100644
index 0000000..d1fd162
--- /dev/null
+++ b/modules/payment/commerce_payment.links.menu.yml
@@ -0,0 +1,5 @@
+entity.commerce_payment_gateway.collection:
+  title: 'Payment gateways'
+  route_name: 'entity.commerce_payment_gateway.collection'
+  parent: 'commerce.configuration'
+  description: 'Manage your payment gateways.'
diff --git a/modules/payment/commerce_payment.links.task.yml b/modules/payment/commerce_payment.links.task.yml
new file mode 100644
index 0000000..4a851e8
--- /dev/null
+++ b/modules/payment/commerce_payment.links.task.yml
@@ -0,0 +1,4 @@
+entity.commerce_payment_gateway.edit_form:
+  route_name: entity.commerce_payment_gateway.edit_form
+  base_route: entity.commerce_payment_gateway.edit_form
+  title: Edit
diff --git a/modules/payment/commerce_payment.module b/modules/payment/commerce_payment.module
new file mode 100755
index 0000000..eab7922
--- /dev/null
+++ b/modules/payment/commerce_payment.module
@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Provides payment functionality.
+ */
+
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+
+/**
+ * Implements hook_entity_base_field_info().
+ */
+function commerce_payment_entity_base_field_info(EntityTypeInterface $entity_type) {
+  if ($entity_type->id() === 'commerce_order') {
+    $fields['payment_gateway'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Payment gateway'))
+      ->setDescription(t('The payment gateway.'))
+      ->setRequired(TRUE)
+      ->setSetting('target_type', 'commerce_payment_gateway');
+
+    $fields['payment_method'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Payment method'))
+      ->setDescription(t('The payment method.'))
+      ->setRequired(TRUE)
+      ->setSetting('target_type', 'commerce_payment_method');
+  }
+}
diff --git a/modules/payment/commerce_payment.permissions.yml b/modules/payment/commerce_payment.permissions.yml
new file mode 100644
index 0000000..5b0aaf7
--- /dev/null
+++ b/modules/payment/commerce_payment.permissions.yml
@@ -0,0 +1,7 @@
+administer payment gateways:
+  title: 'Administer payment gateways'
+  'restrict access': TRUE
+
+administer payments:
+  title: 'Administer payments'
+  'restrict access': TRUE
diff --git a/modules/payment/commerce_payment.routing.yml b/modules/payment/commerce_payment.routing.yml
new file mode 100644
index 0000000..874b79b
--- /dev/null
+++ b/modules/payment/commerce_payment.routing.yml
@@ -0,0 +1,7 @@
+entity.commerce_payment_gateway.collection:
+  path: '/admin/commerce/config/payment-gateways'
+  defaults:
+    _entity_list: 'commerce_payment_gateway'
+    _title: 'Payment gateways'
+  requirements:
+    _permission: 'administer payment gateways'
diff --git a/modules/payment/commerce_payment.services.yml b/modules/payment/commerce_payment.services.yml
new file mode 100644
index 0000000..4336693
--- /dev/null
+++ b/modules/payment/commerce_payment.services.yml
@@ -0,0 +1,12 @@
+services:
+  plugin.manager.commerce_payment_gateway:
+    class: Drupal\commerce_payment\PaymentGatewayManager
+    parent: default_plugin_manager
+
+  plugin.manager.commerce_payment_method_type:
+    class: Drupal\commerce_payment\PaymentMethodTypeManager
+    parent: default_plugin_manager
+
+  plugin.manager.commerce_payment_type:
+    class: Drupal\commerce_payment\PaymentTypeManager
+    parent: default_plugin_manager
diff --git a/modules/payment/commerce_payment.workflow_groups.yml b/modules/payment/commerce_payment.workflow_groups.yml
new file mode 100644
index 0000000..6db4c4c
--- /dev/null
+++ b/modules/payment/commerce_payment.workflow_groups.yml
@@ -0,0 +1,3 @@
+payment:
+  label: Payment
+  entity_type: commerce_payment
diff --git a/modules/payment/commerce_payment.workflows.yml b/modules/payment/commerce_payment.workflows.yml
new file mode 100644
index 0000000..1b99254
--- /dev/null
+++ b/modules/payment/commerce_payment.workflows.yml
@@ -0,0 +1,49 @@
+payment_default:
+  id: payment_default
+  group: payment
+  label: 'Default'
+  states:
+    new:
+      label: 'New'
+    authorization:
+      label: 'Authorization'
+    authorization_void:
+      label: 'Authorization (Voided)'
+    authorization_expired:
+      label: 'Authorization (Expired)'
+    capture_completed:
+      label: 'Capture (Completed)'
+    capture_partally_refunded:
+      label: 'Capture (Partially refunded)'
+    capture_refunded:
+      label: 'Capture (Refunded)'
+  transitions:
+    # Transitions are required, but aren't actually used in this case.
+    authorize:
+      label: 'Authorize payment'
+      from: [new]
+      to: authorization
+    void:
+      label: 'Void payment'
+      from: [authorization]
+      to: authorization_void
+    expire:
+      label: 'Expire payment'
+      from: [authorization]
+      to: authorization_expired
+    authorize_capture:
+      label: 'Authorize and capture payment'
+      from: [new]
+      to: capture_completed
+    capture:
+      label: 'Capture payment'
+      from: [authorization]
+      to: capture_completed
+    partially_refund:
+      label: 'Partially refund payment'
+      from: [capture_completed]
+      to: capture_partally_refunded
+    refund:
+      label: 'Refund payment'
+      from: [capture_completed, capture_partally_refunded]
+      to: capture_refunded
diff --git a/modules/payment/config/schema/commerce_payment.schema.yml b/modules/payment/config/schema/commerce_payment.schema.yml
new file mode 100644
index 0000000..36a1809
--- /dev/null
+++ b/modules/payment/config/schema/commerce_payment.schema.yml
@@ -0,0 +1,33 @@
+commerce_payment.commerce_payment_gateway.*:
+  type: config_entity
+  label: 'Payment gateway'
+  mapping:
+    id:
+      type: string
+      label: 'Machine-readable name'
+    label:
+      type: label
+      label: 'Label'
+    weight:
+      type: integer
+      label: 'Weight'
+    plugin:
+      type: string
+      label: 'Plugin'
+    configuration:
+      type: commerce_payment.commerce_payment_gateway.plugin.[%parent.plugin]
+
+commerce_payment.commerce_payment_gateway.plugin.*:
+  type: commerce_payment_gateway_configuration
+
+commerce_payment_gateway_configuration:
+  type: mapping
+  mapping:
+    mode:
+      type: string
+      label: 'Mode'
+    payment_method_types:
+      type: sequence
+      label: 'Payment method types'
+      sequence:
+        type: string
diff --git a/modules/payment/src/Annotation/CommercePaymentGateway.php b/modules/payment/src/Annotation/CommercePaymentGateway.php
new file mode 100644
index 0000000..a629b13
--- /dev/null
+++ b/modules/payment/src/Annotation/CommercePaymentGateway.php
@@ -0,0 +1,97 @@
+<?php
+
+namespace Drupal\commerce_payment\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines the payment gateway plugin annotation object.
+ *
+ * Plugin namespace: Plugin\Commerce\PaymentGateway.
+ *
+ * @see plugin_api
+ *
+ * @Annotation
+ */
+class CommercePaymentGateway extends Plugin {
+
+  /**
+   * The plugin ID.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * The payment gateway label.
+   *
+   * @ingroup plugin_translatable
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   */
+  public $label;
+
+  /**
+   * The payment gateway display label.
+   *
+   * @ingroup plugin_translatable
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   */
+  public $display_label;
+
+  /**
+   * The supported modes.
+   *
+   * An array of mode labels keyed by machine name.
+   *
+   * @var string[]
+   */
+  public $modes;
+
+  /**
+   * The payment gateway forms.
+   *
+   * An array of form classes keyed by form ID.
+   * For example:
+   * <code>
+   *   'add-payment-method' => "Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\Form\PaymentMethodAddForm",
+   *   'capture-payment' => "Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\Form\PaymentCaptureForm",
+   * </code>
+   *
+   * @var array
+   */
+  public $forms = [];
+
+  /**
+   * The payment type used by the payment gateway.
+   *
+   * @var string
+   */
+  public $payment_type = 'payment_default';
+
+  /**
+   * The payment method types handled by the payment gateway.
+   *
+   * @var string[]
+   */
+  public $payment_method_types = [];
+
+  /**
+   * Constructs a new CommercePaymentGateway object.
+   *
+   * @param array $values
+   *   The annotation values.
+   */
+  public function __construct($values) {
+    // Define default modes.
+    if (empty($values['modes'])) {
+      $values['modes'] = [
+        'test' => t('Test'),
+        'live' => t('Live'),
+      ];
+    }
+    parent::__construct($values);
+  }
+
+}
diff --git a/modules/payment/src/Annotation/CommercePaymentMethodType.php b/modules/payment/src/Annotation/CommercePaymentMethodType.php
new file mode 100644
index 0000000..1a8e91c
--- /dev/null
+++ b/modules/payment/src/Annotation/CommercePaymentMethodType.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Drupal\commerce_payment\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines the payment method type plugin annotation object.
+ *
+ * Plugin namespace: Plugin\Commerce\PaymentMethodType.
+ *
+ * @see plugin_api
+ *
+ * @Annotation
+ */
+class CommercePaymentMethodType extends Plugin {
+
+  /**
+   * The plugin ID.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * The payment method type label.
+   *
+   * @ingroup plugin_translatable
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   */
+  public $label;
+
+  /**
+   * The payment method type create label.
+   *
+   * @ingroup plugin_translatable
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   */
+  public $create_label;
+
+}
diff --git a/modules/payment/src/Annotation/CommercePaymentType.php b/modules/payment/src/Annotation/CommercePaymentType.php
new file mode 100644
index 0000000..07479a2
--- /dev/null
+++ b/modules/payment/src/Annotation/CommercePaymentType.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace Drupal\commerce_payment\Annotation;
+
+use Drupal\Component\Annotation\Plugin;
+
+/**
+ * Defines the payment type plugin annotation object.
+ *
+ * Plugin namespace: Plugin\Commerce\PaymentType.
+ *
+ * @see plugin_api
+ *
+ * @Annotation
+ */
+class CommercePaymentType extends Plugin {
+
+  /**
+   * The plugin ID.
+   *
+   * @var string
+   */
+  public $id;
+
+  /**
+   * The payment type label.
+   *
+   * @ingroup plugin_translatable
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   */
+  public $label;
+
+  /**
+   * The payment workflow.
+   *
+   * @var string
+   */
+  public $workflow = 'payment_default';
+
+}
diff --git a/modules/payment/src/CreditCard.php b/modules/payment/src/CreditCard.php
new file mode 100644
index 0000000..d49d59c
--- /dev/null
+++ b/modules/payment/src/CreditCard.php
@@ -0,0 +1,230 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+/**
+ * Provides logic for listing card types and validating card details.
+ */
+final class CreditCard {
+
+  /**
+   * The instantiated credit card types.
+   *
+   * @var \Drupal\commerce_payment\CreditCardType[]
+   */
+  public static $types = [];
+
+  /**
+   * Gets the credit card type with the given ID.
+   *
+   * @param string $id
+   *   The credit card type ID. For example: 'visa'.
+   *
+   * @return \Drupal\commerce_payment\CreditCardType
+   *   The credit card type.
+   */
+  public static function getType($id) {
+    $types = self::getTypes();
+    if (!isset($types[$id])) {
+      throw new \InvalidArgumentException(sprintf('Invalid credit card type "%s"', $id));
+    }
+
+    return $types[$id];
+  }
+
+  /**
+   * Gets all available credit card types.
+   *
+   * @return \Drupal\commerce_payment\CreditCardType[]
+   *   The credit card types.
+   */
+  public static function getTypes() {
+    $definitions = [
+      'visa' => [
+        'id' => 'visa',
+        'label' => t('Visa'),
+        'number_prefixes' => ['4'],
+      ],
+      'mastercard' => [
+        'id' => 'mastercard',
+        'label' => t('MasterCard'),
+        'number_prefixes' => ['51-55', '222100-272099'],
+      ],
+      'amex' => [
+        'id' => 'amex',
+        'label' => t('American Express'),
+        'number_prefixes' => ['34', '37'],
+        'number_lengths' => [15],
+        'security_code_length' => 4,
+      ],
+      'dinersclub' => [
+        'id' => 'dinersclub',
+        'label' => t('Diners Club'),
+        'number_prefixes' => ['300-305', '309', '36', '38', '39'],
+        'number_lengths' => [14],
+      ],
+      'discover' => [
+        'id' => 'discover',
+        'label' => t('Discover Card'),
+        'number_prefixes' => ['6011', '622126-622925', '644-649', '65'],
+        'number_lengths' => [16, 19],
+      ],
+      'jcb' => [
+        'id' => 'jcb',
+        'label' => t('JCB'),
+        'number_prefixes' => ['3528-3589'],
+      ],
+      'unionpay' => [
+        'id' => 'unionpay',
+        'label' => t('UnionPay'),
+        'number_prefixes' => ['62', '88'],
+        'number_lengths' => [16, 17, 18, 19],
+        'uses_luhn' => FALSE,
+      ],
+      'maestro' => [
+        'id' => 'maestro',
+        'label' => t('Maestro'),
+        'number_prefixes' => [
+          '5018', '5020', '5038', '5612', '5893', '6304',
+          '6759', '6761', '6762', '6763', '0604', '6390',
+        ],
+        'number_lengths' => [12, 13, 14, 15, 16, 17, 18, 19],
+      ],
+    ];
+    foreach ($definitions as $id => $definition) {
+      self::$types[$id] = new CreditCardType($definition);
+    }
+
+    return self::$types;
+  }
+
+  /**
+   * Gets the labels of all available credit card types.
+   *
+   * @return array
+   *   The labels, keyed by ID.
+   */
+  public static function getTypeLabels() {
+    $types = self::getTypes();
+    $type_labels = array_map(function ($type) {
+      return $type->getLabel();
+    }, $types);
+
+    return $type_labels;
+  }
+
+  /**
+   * Detects the credit card type based on the number.
+   *
+   * @param string $number
+   *   The credit card number.
+   *
+   * @return \Drupal\commerce_payment\CreditCardType|null
+   *   The credit card type, or NULL if unknown.
+   */
+  public static function detectType($number) {
+    if (!is_numeric($number)) {
+      return FALSE;
+    }
+    $types = self::getTypes();
+    foreach ($types as $type) {
+      foreach ($type->getNumberPrefixes() as $prefix) {
+        if (self::matchPrefix($number, $prefix)) {
+          return $type;
+        }
+      }
+    }
+
+    return FALSE;
+  }
+
+  /**
+   * Checks whether the given credit card number matches the given prefix.
+   *
+   * @param string $number
+   *   The credit card number.
+   * @param string $prefix
+   *   The prefix to match against. Can be a single number such as '43' or a
+   *   range such as '30-35'.
+   *
+   * @return bool
+   *   TRUE if the credit card number matches the prefix, FALSE otherwise.
+   */
+  public static function matchPrefix($number, $prefix) {
+    if (is_numeric($prefix)) {
+      return substr($number, 0, strlen($prefix)) == $prefix;
+    }
+    else {
+      list($start, $end) = explode('-', $prefix);
+      $number = substr($number, 0, strlen($start));
+      return $number >= $start && $number <= $end;
+    }
+  }
+
+  /**
+   * Validates the given credit card number.
+   *
+   * @param string $number
+   *   The credit card number.
+   * @param \Drupal\commerce_payment\CreditCardType $type
+   *   The credit card type.
+   *
+   * @return bool
+   *   TRUE if the credit card number is valid, FALSE otherwise.
+   */
+  public static function validateNumber($number, CreditCardType $type) {
+    if (!is_numeric($number)) {
+      return FALSE;
+    }
+    if (!in_array(strlen($number), $type->getNumberLengths())) {
+      return FALSE;
+    }
+    if ($type->usesLuhn() && !self::validateLuhn($number)) {
+      return FALSE;
+    }
+
+    return TRUE;
+  }
+
+  /**
+   * Validates the given credit card number using the Luhn algorithm.
+   *
+   * @param string $number
+   *   The credit card number.
+   *
+   * @return bool
+   *   TRUE if the credit card number is valid, FALSE otherwise.
+   */
+  public static function validateLuhn($number) {
+    $total = 0;
+    foreach (array_reverse(str_split($number)) as $i => $digit) {
+      $digit = $i % 2 ? $digit * 2 : $digit;
+      $digit = $digit > 9 ? $digit - 9 : $digit;
+      $total += $digit;
+    }
+    return ($total % 10 === 0);
+  }
+
+  /**
+   * Validates the given credit card security code.
+   *
+   * @param string $security_code
+   *   The credit card security code.
+   * @param \Drupal\commerce_payment\CreditCardType $type
+   *   The credit card type.
+   *
+   * @return bool
+   *   TRUE if the credit card security code is valid, FALSE otherwise.
+   */
+  public static function validateSecurityCode($security_code, CreditCardType $type) {
+    if (!is_numeric($security_code)) {
+      return FALSE;
+    }
+    if (strlen($security_code) != $type->getSecurityCodeLength()) {
+      return FALSE;
+    }
+
+    return TRUE;
+  }
+
+}
diff --git a/modules/payment/src/CreditCardType.php b/modules/payment/src/CreditCardType.php
new file mode 100644
index 0000000..7b6b563
--- /dev/null
+++ b/modules/payment/src/CreditCardType.php
@@ -0,0 +1,139 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+/**
+ * Represents a credit card type.
+ */
+final class CreditCardType {
+
+  /**
+   * The credit card type ID.
+   *
+   * @var string
+   */
+  protected $id;
+
+  /**
+   * The credit card type label.
+   *
+   * @var string
+   */
+  protected $label;
+
+  /**
+   * The credit card type number prefixes.
+   *
+   * @var array
+   */
+  protected $numberPrefixes;
+
+  /**
+   * The credit card type number lengths.
+   *
+   * @var array
+   */
+  protected $numberLengths = [16];
+
+  /**
+   * The credit card type security code length.
+   *
+   * @var string
+   */
+  protected $securityCodeLength = 3;
+
+  /**
+   * Whether the credit cart type uses Luhn validation.
+   *
+   * @var string
+   */
+  protected $usesLuhn = TRUE;
+
+  /**
+   * Constructs a new CreditCardType instance.
+   *
+   * @param array $definition
+   *   The definition.
+   */
+  public function __construct(array $definition) {
+    foreach (['id', 'label', 'number_prefixes'] as $required_property) {
+      if (empty($definition[$required_property])) {
+        throw new \InvalidArgumentException(sprintf('Missing required property %s.', $required_property));
+      }
+    }
+
+    $this->id = $definition['id'];
+    $this->label = $definition['label'];
+    $this->numberPrefixes = $definition['number_prefixes'];
+    if (isset($definition['number_lengths'])) {
+      $this->numberLengths = $definition['number_lengths'];
+    }
+    if (isset($definition['security_code_length'])) {
+      $this->securityCodeLength = $definition['security_code_length'];
+    }
+    if (isset($definition['uses_luhn'])) {
+      $this->usesLuhn = $definition['uses_luhn'];
+    }
+  }
+
+  /**
+   * Gets the credit card type ID.
+   *
+   * @return string
+   *   The credit card type ID.
+   */
+  public function getId() {
+    return $this->id;
+  }
+
+  /**
+   * Gets the credit card type label.
+   *
+   * @return string
+   *   The credit card type label.
+   */
+  public function getLabel() {
+    return $this->label;
+  }
+
+  /**
+   * Gets the credit card type number prefixes.
+   *
+   * @return array
+   *   The credit card type number prefixes.
+   */
+  public function getNumberPrefixes() {
+    return $this->numberPrefixes;
+  }
+
+  /**
+   * Gets the credit card type number lengths.
+   *
+   * @return array
+   *   The credit card type number lengths.
+   */
+  public function getNumberLengths() {
+    return $this->numberLengths;
+  }
+
+  /**
+   * Gets the credit card type security code length.
+   *
+   * @return string
+   *   The credit card type security code length.
+   */
+  public function getSecurityCodeLength() {
+    return $this->securityCodeLength;
+  }
+
+  /**
+   * Gets whether the credit card type uses Luhn validation.
+   *
+   * @return bool
+   *   TRUE if the credit card type uses Luhn validation, FALSE otherwise.
+   */
+  public function usesLuhn() {
+    return $this->usesLuhn;
+  }
+
+}
diff --git a/modules/payment/src/Entity/Payment.php b/modules/payment/src/Entity/Payment.php
new file mode 100644
index 0000000..26e229e
--- /dev/null
+++ b/modules/payment/src/Entity/Payment.php
@@ -0,0 +1,266 @@
+<?php
+
+namespace Drupal\commerce_payment\Entity;
+
+use Drupal\commerce_price\Price;
+use Drupal\Core\Entity\ContentEntityBase;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+
+/**
+ * Defines the payment entity class.
+ *
+ * @ContentEntityType(
+ *   id = "commerce_payment",
+ *   label = @Translation("Payment"),
+ *   label_singular = @Translation("Payment"),
+ *   label_plural = @Translation("Payments"),
+ *   label_count = @PluralTranslation(
+ *     singular = "@count payment",
+ *     plural = "@count payments",
+ *   ),
+ *   bundle_label = @Translation("Payment type"),
+ *   bundle_plugin_type = "commerce_payment_type",
+ *   handlers = {
+ *     "storage" = "Drupal\commerce_payment\PaymentStorage",
+ *     "views_data" = "Drupal\views\EntityViewsData",
+ *   },
+ *   base_table = "commerce_payment",
+ *   admin_permission = "administer payments",
+ *   fieldable = TRUE,
+ *   entity_keys = {
+ *     "id" = "payment_id",
+ *     "bundle" = "payment_gateway",
+ *     "uuid" = "uuid",
+ *   },
+ * )
+ */
+class Payment extends ContentEntityBase implements PaymentInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getType() {
+    $payment_type_manager = \Drupal::service('plugin.manager.commerce_payment_type');
+    return $payment_type_manager->createInstance($this->bundle());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentGateway() {
+    return $this->get('payment_gateway')->entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentGatewayId() {
+    return $this->get('payment_gateway')->target_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentMethod() {
+    return $this->get('payment_method')->entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentMethodId() {
+    return $this->get('payment_method')->target_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getOrder() {
+    return $this->get('order_id')->entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getOrderId() {
+    return $this->get('order_id')->target_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRemoteId() {
+    return $this->get('remote_id')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setRemoteId($remote_id) {
+    $this->set('remote_id', $remote_id);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getAmount() {
+    return $this->get('amount')->first()->toPrice();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setAmount(Price $amount) {
+    $this->set('amount', $amount);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRefundedAmount() {
+    return $this->get('refunded_amount')->first()->toPrice();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setRefundedAmount(Price $refunded_amount) {
+    $this->set('refunded_amount', $refunded_amount);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getState() {
+    return $this->get('state')->first();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getAuthorizedTime() {
+    return $this->get('authorized')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setAuthorizedTime($timestamp) {
+    $this->set('authorized', $timestamp);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getAuthorizationExpiresTime() {
+    return $this->get('authorization_expires')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setAuthorizationExpiresTime($timestamp) {
+    $this->set('authorization_expires', $timestamp);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCapturedTime() {
+    return $this->get('captured')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setCapturedTime($timestamp) {
+    $this->set('captured', $timestamp);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
+    $fields = parent::baseFieldDefinitions($entity_type);
+
+    $fields['payment_method'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Payment method'))
+      ->setDescription(t('The payment method.'))
+      ->setSetting('target_type', 'commerce_payment_method')
+      ->setReadOnly(TRUE);
+
+    $fields['order_id'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Order'))
+      ->setDescription(t('The parent order.'))
+      ->setSetting('target_type', 'commerce_order')
+      ->setReadOnly(TRUE);
+
+    $fields['remote_id'] = BaseFieldDefinition::create('string')
+      ->setLabel(t('Remote ID'))
+      ->setDescription(t('The remote payment ID.'))
+      ->setSetting('max_length', 255)
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['amount'] = BaseFieldDefinition::create('commerce_price')
+      ->setLabel(t('Amount'))
+      ->setDescription(t('The payment amount.'))
+      ->setRequired(TRUE)
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['refunded_amount'] = BaseFieldDefinition::create('commerce_price')
+      ->setLabel(t('Refunded amount'))
+      ->setDescription(t('The refunded payment amount.'))
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['state'] = BaseFieldDefinition::create('state')
+      ->setLabel(t('State'))
+      ->setDescription(t('The payment state.'))
+      ->setRequired(TRUE)
+      ->setSetting('max_length', 255)
+      ->setDisplayOptions('view', [
+        'label' => 'hidden',
+        'type' => 'list_default',
+        'weight' => 0,
+      ])
+      ->setDisplayConfigurable('view', TRUE)
+      ->setSetting('workflow_callback', ['\Drupal\commerce_payment\Entity\Payment', 'getWorkflowId']);
+
+    $fields['authorized'] = BaseFieldDefinition::create('timestamp')
+      ->setLabel(t('Authorized'))
+      ->setDescription(t('The time when the payment was authorized.'))
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['authorization_expires'] = BaseFieldDefinition::create('timestamp')
+      ->setLabel(t('Authorization expires'))
+      ->setDescription(t('The time when the payment authorization expires.'))
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['captured'] = BaseFieldDefinition::create('timestamp')
+      ->setLabel(t('Captured'))
+      ->setDescription(t('The time when the payment was captured.'))
+      ->setDisplayConfigurable('view', TRUE);
+
+    return $fields;
+  }
+
+  /**
+   * Gets the workflow ID for the state field.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentInterface $payment
+   *   The payment.
+   *
+   * @return string
+   *   The workflow ID.
+   */
+  public static function getWorkflowId(PaymentInterface $payment) {
+    return $payment->getType()->getWorkflowId();
+  }
+
+}
diff --git a/modules/payment/src/Entity/PaymentGateway.php b/modules/payment/src/Entity/PaymentGateway.php
new file mode 100644
index 0000000..7e9c87c
--- /dev/null
+++ b/modules/payment/src/Entity/PaymentGateway.php
@@ -0,0 +1,161 @@
+<?php
+
+namespace Drupal\commerce_payment\Entity;
+
+use Drupal\commerce_payment\PaymentGatewayPluginCollection;
+use Drupal\Core\Config\Entity\ConfigEntityBase;
+
+/**
+ * Defines the payment gateway entity class.
+ *
+ * @ConfigEntityType(
+ *   id = "commerce_payment_gateway",
+ *   label = @Translation("Payment gateway"),
+ *   label_singular = @Translation("Payment gateway"),
+ *   label_plural = @Translation("Payment gateways"),
+ *   label_count = @PluralTranslation(
+ *     singular = "@count payment gateway",
+ *     plural = "@count payment gateways",
+ *   ),
+ *   handlers = {
+ *     "list_builder" = "Drupal\commerce_payment\PaymentGatewayListBuilder",
+ *     "form" = {
+ *       "add" = "Drupal\commerce_payment\Form\PaymentGatewayForm",
+ *       "edit" = "Drupal\commerce_payment\Form\PaymentGatewayForm",
+ *       "delete" = "Drupal\Core\Entity\EntityDeleteForm"
+ *     },
+ *     "route_provider" = {
+ *       "default" = "Drupal\Core\Entity\Routing\DefaultHtmlRouteProvider",
+ *     },
+ *   },
+ *   admin_permission = "administer payment gateways",
+ *   config_prefix = "commerce_payment_gateway",
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "label" = "label",
+ *     "uuid" = "uuid",
+ *     "weight" = "weight",
+ *   },
+ *   config_export = {
+ *     "id",
+ *     "label",
+ *     "weight",
+ *     "plugin",
+ *     "configuration",
+ *   },
+ *   links = {
+ *     "add-form" = "/admin/commerce/config/payment-gateways/add",
+ *     "edit-form" = "/admin/commerce/config/payment-gateways/manage/{commerce_payment_gateway}",
+ *     "delete-form" = "/admin/commerce/config/payment-gateways/manage/{commerce_payment_gateway}/delete",
+ *     "collection" =  "/admin/commerce/config/payment-gateways"
+ *   }
+ * )
+ */
+class PaymentGateway extends ConfigEntityBase implements PaymentGatewayInterface {
+
+  /**
+   * The payment gateway ID.
+   *
+   * @var string
+   */
+  protected $id;
+
+  /**
+   * The payment gateway label.
+   *
+   * @var string
+   */
+  protected $label;
+
+  /**
+   * The payment gateway weight.
+   *
+   * @var int
+   */
+  protected $weight;
+
+  /**
+   * The plugin ID.
+   *
+   * @var string
+   */
+  protected $plugin;
+
+  /**
+   * The plugin configuration.
+   *
+   * @var array
+   */
+  protected $configuration = [];
+
+  /**
+   * The plugin collection that holds the payment gateway plugin.
+   *
+   * @var \Drupal\commerce_payment\PaymentGatewayPluginCollection
+   */
+  protected $pluginCollection;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getWeight() {
+    return $this->weight;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setWeight($weight) {
+    $this->weight = $weight;
+    return $weight;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPlugin() {
+    return $this->getPluginCollection()->get($this->plugin);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPluginId() {
+    return $this->plugin;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setPluginId($plugin_id) {
+    $this->plugin = $plugin_id;
+    $this->pluginCollection = NULL;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPluginCollections() {
+    return [
+      'configuration' => $this->getPluginCollection(),
+    ];
+  }
+
+  /**
+   * Gets the plugin collection that holds the payment gateway plugin.
+   *
+   * Ensures the plugin collection is initialized before returning it.
+   *
+   * @return \Drupal\commerce_payment\PaymentGatewayPluginCollection
+   *   The plugin collection.
+   */
+  protected function getPluginCollection() {
+    if (!$this->pluginCollection) {
+      $plugin_manager = \Drupal::service('plugin.manager.commerce_payment_gateway');
+      $this->pluginCollection = new PaymentGatewayPluginCollection($plugin_manager, $this->plugin, $this->configuration, $this->id);
+    }
+    return $this->pluginCollection;
+  }
+
+}
diff --git a/modules/payment/src/Entity/PaymentGatewayInterface.php b/modules/payment/src/Entity/PaymentGatewayInterface.php
new file mode 100644
index 0000000..1ab4100
--- /dev/null
+++ b/modules/payment/src/Entity/PaymentGatewayInterface.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace Drupal\commerce_payment\Entity;
+
+use Drupal\Core\Config\Entity\ConfigEntityInterface;
+use Drupal\Core\Entity\EntityWithPluginCollectionInterface;
+
+/**
+ * Defines the interface for payment gateway configuration entities.
+ *
+ * Stores configuration for payment gateway plugins.
+ */
+interface PaymentGatewayInterface extends ConfigEntityInterface, EntityWithPluginCollectionInterface {
+
+  /**
+   * Gets the payment gateway weight.
+   *
+   * @return string
+   *   The payment gateway weight.
+   */
+  public function getWeight();
+
+  /**
+   * Sets the payment gateway weight.
+   *
+   * @param int $weight
+   *   The payment gateway weight.
+   *
+   * @return $this
+   */
+  public function setWeight($weight);
+
+  /**
+   * Gets the payment gateway plugin.
+   *
+   * @return \Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\PaymentGatewayInterface
+   *   The payment gateway plugin.
+   */
+  public function getPlugin();
+
+  /**
+   * Gets the payment gateway plugin ID.
+   *
+   * @return string
+   *   The payment gateway plugin ID.
+   */
+  public function getPluginId();
+
+  /**
+   * Sets the payment gateway plugin ID.
+   *
+   * @param string $plugin_id
+   *   The payment gateway plugin ID.
+   *
+   * @return $this
+   */
+  public function setPluginId($plugin_id);
+
+}
diff --git a/modules/payment/src/Entity/PaymentInterface.php b/modules/payment/src/Entity/PaymentInterface.php
new file mode 100644
index 0000000..c181be4
--- /dev/null
+++ b/modules/payment/src/Entity/PaymentInterface.php
@@ -0,0 +1,185 @@
+<?php
+
+namespace Drupal\commerce_payment\Entity;
+
+use Drupal\commerce_price\Price;
+use Drupal\Core\Entity\ContentEntityInterface;
+
+/**
+ * Defines the interface for payments.
+ */
+interface PaymentInterface extends ContentEntityInterface {
+
+  /**
+   * Gets the payment type.
+   *
+   * @return \Drupal\commerce_payment\Plugin\Commerce\PaymentType\PaymentTypeInterface
+   *   The payment type.
+   */
+  public function getType();
+
+  /**
+   * Gets the payment gateway.
+   *
+   * @return \Drupal\commerce_payment\Entity\PaymentGatewayInterface|null
+   *   The payment gateway entity, or null if unknown.
+   */
+  public function getPaymentGateway();
+
+  /**
+   * Gets the payment gateway ID.
+   *
+   * @return int|null
+   *   The payment gateway ID, or null if unknown.
+   */
+  public function getPaymentGatewayId();
+
+  /**
+   * Gets the payment method.
+   *
+   * @return \Drupal\commerce_payment\Entity\PaymentMethodInterface|null
+   *   The payment method entity, or null if unknown.
+   */
+  public function getPaymentMethod();
+
+  /**
+   * Gets the payment method ID.
+   *
+   * @return int|null
+   *   The payment method ID, or null if unknown.
+   */
+  public function getPaymentMethodId();
+
+  /**
+   * Gets the parent order.
+   *
+   * @return \Drupal\commerce_order\Entity\OrderInterface|null
+   *   The order entity, or null.
+   */
+  public function getOrder();
+
+  /**
+   * Gets the parent order ID.
+   *
+   * @return int|null
+   *   The order ID, or null.
+   */
+  public function getOrderId();
+
+  /**
+   * Gets the payment remote ID.
+   *
+   * @return string
+   *   The payment remote ID.
+   */
+  public function getRemoteId();
+
+  /**
+   * Sets the payment remote ID.
+   *
+   * @param string $remote_ID
+   *   The payment remote ID.
+   *
+   * @return $this
+   */
+  public function setRemoteId($remote_ID);
+
+  /**
+   * Gets the payment amount.
+   *
+   * @return \Drupal\commerce_price\Price
+   *   The payment amount.
+   */
+  public function getAmount();
+
+  /**
+   * Sets the payment amount.
+   *
+   * @param \Drupal\commerce_price\Price $amount
+   *   The payment amount.
+   *
+   * @return $this
+   */
+  public function setAmount(Price $amount);
+
+  /**
+   * Gets the refunded payment amount.
+   *
+   * @return \Drupal\commerce_price\Price
+   *   The refunded payment amount.
+   */
+  public function getRefundedAmount();
+
+  /**
+   * Sets the refunded payment amount.
+   *
+   * @param \Drupal\commerce_price\Price $refunded_amount
+   *   The refunded payment amount.
+   *
+   * @return $this
+   */
+  public function setRefundedAmount(Price $refunded_amount);
+
+  /**
+   * Gets the payment state.
+   *
+   * @return \Drupal\state_machine\Plugin\Field\FieldType\StateItemInterface
+   *   The payment state.
+   */
+  public function getState();
+
+  /**
+   * Gets the payment authorization timestamp.
+   *
+   * @return int
+   *   The payment authorization timestamp.
+   */
+  public function getAuthorizedTime();
+
+  /**
+   * Sets the payment authorization timestamp.
+   *
+   * @param int $timestamp
+   *   The payment authorization timestamp.
+   *
+   * @return $this
+   */
+  public function setAuthorizedTime($timestamp);
+
+  /**
+   * Gets the payment authorization expiration timestamp.
+   *
+   * @return int
+   *   The payment authorization expiration timestamp.
+   */
+  public function getAuthorizationExpiresTime();
+
+  /**
+   * Sets the payment authorization expiration timestamp.
+   *
+   * @param int $timestamp
+   *   The payment authorization expiration timestamp.
+   *
+   * @return $this
+   */
+  public function setAuthorizationExpiresTime($timestamp);
+
+  /**
+   * Gets the payment capture timestamp.
+   *
+   * @return int
+   *   The payment capture timestamp.
+   */
+  public function getCapturedTime();
+
+  /**
+   * Sets the payment capture timestamp.
+   *
+   * @param int $timestamp
+   *   The payment capture timestamp.
+   *
+   * @return $this
+   */
+  public function setCapturedTime($timestamp);
+
+}
diff --git a/modules/payment/src/Entity/PaymentMethod.php b/modules/payment/src/Entity/PaymentMethod.php
new file mode 100644
index 0000000..9348b84
--- /dev/null
+++ b/modules/payment/src/Entity/PaymentMethod.php
@@ -0,0 +1,290 @@
+<?php
+
+namespace Drupal\commerce_payment\Entity;
+
+use Drupal\Core\Entity\ContentEntityBase;
+use Drupal\Core\Entity\EntityChangedTrait;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+use Drupal\user\UserInterface;
+use Drupal\profile\Entity\ProfileInterface;
+
+/**
+ * Defines the payment method entity class.
+ *
+ * @ContentEntityType(
+ *   id = "commerce_payment_method",
+ *   label = @Translation("Payment method"),
+ *   label_singular = @Translation("Payment method"),
+ *   label_plural = @Translation("Payment methods"),
+ *   label_count = @PluralTranslation(
+ *     singular = "@count payment method",
+ *     plural = "@count payment methods",
+ *   ),
+ *   bundle_label = @Translation("Payment method type"),
+ *   bundle_plugin_type = "commerce_payment_method_type",
+ *   handlers = {
+ *     "storage" = "Drupal\commerce_payment\PaymentMethodStorage",
+ *   },
+ *   base_table = "commerce_payment_method",
+ *   admin_permission = "administer payments",
+ *   fieldable = TRUE,
+ *   entity_keys = {
+ *     "id" = "method_id",
+ *     "uuid" = "uuid",
+ *     "bundle" = "type"
+ *   },
+ * )
+ */
+class PaymentMethod extends ContentEntityBase implements PaymentMethodInterface {
+
+  use EntityChangedTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function label() {
+    return $this->getType()->buildLabel($this);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getType() {
+    $payment_method_type_manager = \Drupal::service('plugin.manager.commerce_payment_method_type');
+    return $payment_method_type_manager->createInstance($this->bundle());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentGateway() {
+    return $this->get('payment_gateway')->entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentGatewayId() {
+    return $this->get('payment_gateway')->target_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getOwner() {
+    return $this->get('uid')->entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getOwnerId() {
+    return $this->get('uid')->target_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setOwnerId($uid) {
+    $this->set('uid', $uid);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setOwner(UserInterface $account) {
+    $this->set('uid', $account->id());
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getRemoteId() {
+    return $this->get('remote_id')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setRemoteId($remote_id) {
+    $this->set('remote_id', $remote_id);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getBillingProfile() {
+    return $this->get('billing_profile')->entity;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setBillingProfile(ProfileInterface $profile) {
+    $this->set('billing_profile', $profile->id());
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getBillingProfileId() {
+    return $this->get('billing_profile')->target_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setBillingProfileId($billingProfileId) {
+    $this->set('billing_profile', $billingProfileId);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isReusable() {
+    return $this->get('reusable')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setReusable($reusable) {
+    $this->set('reusable', $reusable);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isDefault() {
+    return $this->get('is_default')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setDefault($default) {
+    $this->set('is_default', $default);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getExpiresTime() {
+    return $this->get('expires')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setExpiresTime($timestamp) {
+    $this->set('expires', $timestamp);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCreatedTime() {
+    return $this->get('created')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setCreatedTime($timestamp) {
+    $this->set('created', $timestamp);
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
+    $fields = parent::baseFieldDefinitions($entity_type);
+
+    $fields['payment_gateway'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Payment gateway'))
+      ->setDescription(t('The payment gateway.'))
+      ->setRequired(TRUE)
+      ->setSetting('target_type', 'commerce_payment_gateway');
+
+    $fields['uid'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Owner'))
+      ->setDescription(t('The payment method owner.'))
+      ->setSetting('target_type', 'user')
+      ->setSetting('handler', 'default')
+      ->setDefaultValueCallback('Drupal\commerce_payment\Entity\PaymentMethod::getCurrentUserId')
+      ->setDisplayOptions('view', [
+        'label' => 'above',
+        'type' => 'author',
+        'weight' => 0,
+      ])
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['remote_id'] = BaseFieldDefinition::create('string')
+      ->setLabel(t('Remote ID'))
+      ->setDescription(t('The payment method remote ID.'))
+      ->setSetting('max_length', 255)
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['billing_profile'] = BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Billing profile'))
+      ->setDescription(t('Billing profile'))
+      ->setSetting('target_type', 'profile')
+      ->setSetting('handler', 'default')
+      ->setSetting('handler_settings', ['target_bundles' => ['billing']])
+      ->setDisplayOptions('form', [
+        'type' => 'options_select',
+        'weight' => 0,
+        'settings' => [],
+      ])
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['reusable'] = BaseFieldDefinition::create('boolean')
+      ->setLabel(t('Reusable'))
+      ->setDescription(t('Whether the payment method is reusable.'))
+      ->setDefaultValue(TRUE)
+      ->setDisplayConfigurable('view', TRUE);
+
+    // 'default' is a reserved SQL word, hence the 'is_' prefix.
+    $fields['is_default'] = BaseFieldDefinition::create('boolean')
+      ->setLabel(t('Default'))
+      ->setDescription(t("Whether this is the user's default payment method."));
+
+    $fields['expires'] = BaseFieldDefinition::create('timestamp')
+      ->setLabel(t('Expires'))
+      ->setDescription(t('The time when the payment authorization expires.'))
+      ->setDisplayConfigurable('view', TRUE);
+
+    $fields['created'] = BaseFieldDefinition::create('created')
+      ->setLabel(t('Created'))
+      ->setDescription(t('The time when the payment was created.'));
+
+    $fields['changed'] = BaseFieldDefinition::create('changed')
+      ->setLabel(t('Changed'))
+      ->setDescription(t('The time when the payment was last edited.'));
+
+    return $fields;
+  }
+
+  /**
+   * Default value callback for 'uid' base field definition.
+   *
+   * @see ::baseFieldDefinitions()
+   *
+   * @return array
+   *   An array of default values.
+   */
+  public static function getCurrentUserId() {
+    return [\Drupal::currentUser()->id()];
+  }
+
+}
diff --git a/modules/payment/src/Entity/PaymentMethodInterface.php b/modules/payment/src/Entity/PaymentMethodInterface.php
new file mode 100644
index 0000000..3bf181b
--- /dev/null
+++ b/modules/payment/src/Entity/PaymentMethodInterface.php
@@ -0,0 +1,165 @@
+<?php
+
+namespace Drupal\commerce_payment\Entity;
+
+use Drupal\Core\Entity\EntityChangedInterface;
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\user\EntityOwnerInterface;
+use Drupal\profile\Entity\ProfileInterface;
+
+/**
+ * Defines the interface for payment methods.
+ */
+interface PaymentMethodInterface extends EntityChangedInterface, ContentEntityInterface, EntityOwnerInterface {
+
+  /**
+   * Gets the payment method type.
+   *
+   * @return \Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType\PaymentMethodTypeInterface
+   *   The payment method type.
+   */
+  public function getType();
+
+  /**
+   * Gets the payment gateway.
+   *
+   * @return \Drupal\commerce_payment\Entity\PaymentGatewayInterface|null
+   *   The payment gateway entity, or null if unknown.
+   */
+  public function getPaymentGateway();
+
+  /**
+   * Gets the payment gateway ID.
+   *
+   * @return int|null
+   *   The payment gateway ID, or null if unknown.
+   */
+  public function getPaymentGatewayId();
+
+  /**
+   * Gets the payment method remote ID.
+   *
+   * @return string
+   *   The payment method remote ID.
+   */
+  public function getRemoteId();
+
+  /**
+   * Sets the payment method remote ID.
+   *
+   * @param string $remote_id
+   *   The payment method remote ID.
+   *
+   * @return $this
+   */
+  public function setRemoteId($remote_id);
+
+  /**
+   * Gets the billing profile.
+   *
+   * @return \Drupal\profile\Entity\ProfileInterface
+   *   The billing profile entity.
+   */
+  public function getBillingProfile();
+
+  /**
+   * Sets the billing profile.
+   *
+   * @param \Drupal\profile\Entity\ProfileInterface $profile
+   *   The billing profile entity.
+   *
+   * @return $this
+   */
+  public function setBillingProfile(ProfileInterface $profile);
+
+  /**
+   * Gets the billing profile ID.
+   *
+   * @return int
+   *   The billing profile ID.
+   */
+  public function getBillingProfileId();
+
+  /**
+   * Sets the billing profile ID.
+   *
+   * @param int $billingProfileId
+   *   The billing profile ID.
+   *
+   * @return $this
+   */
+  public function setBillingProfileId($billingProfileId);
+
+  /**
+   * Gets whether the payment method is reusable.
+   *
+   * @return bool
+   *   TRUE if the payment method is reusable, FALSE otherwise.
+   */
+  public function isReusable();
+
+  /**
+   * Sets whether the payment method is reusable.
+   *
+   * @param bool $reusable
+   *   Whether the payment method is reusable.
+   *
+   * @return $this
+   */
+  public function setReusable($reusable);
+
+  /**
+   * Gets whether this is the user's default payment method.
+   *
+   * @return bool
+   *   TRUE if this is the user's default payment method, FALSE otherwise.
+   */
+  public function isDefault();
+
+  /**
+   * Sets whether this is the user's default payment method.
+   *
+   * @param bool $default
+   *   Whether this is the user's default payment method.
+   *
+   * @return $this
+   */
+  public function setDefault($default);
+
+  /**
+   * Gets the payment method expiration timestamp.
+   *
+   * @return int
+   *   The payment method expiration timestamp.
+   */
+  public function getExpiresTime();
+
+  /**
+   * Sets the payment method expiration timestamp.
+   *
+   * @param int $timestamp
+   *   The payment method expiration timestamp.
+   *
+   * @return $this
+   */
+  public function setExpiresTime($timestamp);
+
+  /**
+   * Gets the payment method creation timestamp.
+   *
+   * @return int
+   *   Creation timestamp of the payment.
+   */
+  public function getCreatedTime();
+
+  /**
+   * Sets the payment method creation timestamp.
+   *
+   * @param int $timestamp
+   *   The payment method creation timestamp.
+   *
+   * @return $this
+   */
+  public function setCreatedTime($timestamp);
+
+}
diff --git a/modules/payment/src/Form/PaymentGatewayForm.php b/modules/payment/src/Form/PaymentGatewayForm.php
new file mode 100644
index 0000000..c2d2d8d
--- /dev/null
+++ b/modules/payment/src/Form/PaymentGatewayForm.php
@@ -0,0 +1,140 @@
+<?php
+
+namespace Drupal\commerce_payment\Form;
+
+use Drupal\commerce_payment\PaymentGatewayManager;
+use Drupal\Core\Entity\BundleEntityFormBase;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class PaymentGatewayForm extends BundleEntityFormBase {
+
+  /**
+   * The payment gateway plugin manager.
+   *
+   * @var \Drupal\commerce_payment\PaymentGatewayManager
+   */
+  protected $pluginManager;
+
+  /**
+   * Constructs a new PaymentGatewayForm object.
+   *
+   * @param \Drupal\commerce_payment\PaymentGatewayManager $plugin_manager
+   *   The payment gateway plugin manager.
+   */
+  public function __construct(PaymentGatewayManager $plugin_manager) {
+    $this->pluginManager = $plugin_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('plugin.manager.commerce_payment_gateway')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function form(array $form, FormStateInterface $form_state) {
+    $form = parent::form($form, $form_state);
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface $gateway */
+    $gateway = $this->entity;
+    $plugins = array_map(function ($definition) {
+      return $definition['label'];
+    }, $this->pluginManager->getDefinitions());
+
+    $form['#tree'] = TRUE;
+    $form['label'] = [
+      '#type' => 'textfield',
+      '#title' => $this->t('Name'),
+      '#maxlength' => 255,
+      '#default_value' => $gateway->label(),
+      '#required' => TRUE,
+    ];
+    $form['id'] = [
+      '#type' => 'machine_name',
+      '#default_value' => $gateway->id(),
+      '#machine_name' => [
+        'exists' => '\Drupal\commerce_payment\Entity\PaymentGateway::load',
+      ],
+    ];
+    $form['plugin'] = [
+      '#type' => 'select',
+      '#title' => $this->t('Plugin'),
+      '#options' => $plugins,
+      '#default_value' => $gateway->getPluginId(),
+      '#required' => TRUE,
+      '#disabled' => !$gateway->isNew(),
+    ];
+    if (!$gateway->isNew()) {
+      $form['configuration'] = [
+        '#parents' => ['configuration'],
+      ];
+      $form['configuration'] = $gateway->getPlugin()->buildConfigurationForm($form['configuration'], $form_state);
+    }
+
+    // Payment gateway is technically not a bundle config entity, but the logic
+    // for preventing id change on edit applies the same.
+    return $this->protectBundleIdElement($form);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function copyFormValuesToEntity(EntityInterface $entity, array $form, FormStateInterface $form_state) {
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface $entity */
+    // The parent method tries to initialize the plugin collection before
+    // setting the plugin.
+    $entity->setPluginId($form_state->getValue('plugin'));
+
+    parent::copyFormValuesToEntity($entity, $form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateForm(array &$form, FormStateInterface $form_state) {
+    parent::validateForm($form, $form_state);
+
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface $gateway */
+    $gateway = $this->entity;
+    if (!$gateway->isNew()) {
+      $gateway->getPlugin()->validateConfigurationForm($form['configuration'], $form_state);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    parent::submitForm($form, $form_state);
+
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface $gateway */
+    $gateway = $this->entity;
+    if (!$gateway->isNew()) {
+      $gateway->getPlugin()->submitConfigurationForm($form['configuration'], $form_state);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function save(array $form, FormStateInterface $form_state) {
+    $status = $this->entity->save();
+    drupal_set_message($this->t('Saved the %label payment gateway.', ['%label' => $this->entity->label()]));
+    if ($status == SAVED_UPDATED) {
+      $form_state->setRedirect('entity.commerce_payment_gateway.collection');
+    }
+    elseif ($status == SAVED_NEW) {
+      // Send the user to the Edit form to see the plugin configuration form.
+      $form_state->setRedirect('entity.commerce_payment_gateway.edit_form', [
+        'commerce_payment_gateway' => $this->entity->id(),
+      ]);
+    }
+  }
+
+}
diff --git a/modules/payment/src/PaymentGatewayListBuilder.php b/modules/payment/src/PaymentGatewayListBuilder.php
new file mode 100644
index 0000000..b28b87d
--- /dev/null
+++ b/modules/payment/src/PaymentGatewayListBuilder.php
@@ -0,0 +1,66 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\Core\Config\Entity\DraggableListBuilder;
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Defines the list builder for payment gateways.
+ */
+class PaymentGatewayListBuilder extends DraggableListBuilder {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected $entitiesKey = 'gateways';
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'commerce_payment_gateways';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildHeader() {
+    $header['label'] = $this->t('Payment gateway');
+    $header['mode'] = $this->t('Mode');
+    return $header + parent::buildHeader();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildRow(EntityInterface $entity) {
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface $entity */
+    $gateway_plugin = $entity->getPlugin();
+    $modes = $gateway_plugin->getSupportedModes();
+    $mode = $modes ? $modes[$gateway_plugin->getMode()] : $this->t('N/A');
+    $row['label'] = $entity->label();
+    // $this->weightKey determines whether the table will be rendered as a form.
+    if (!empty($this->weightKey)) {
+      $row['mode']['#markup'] = $mode;
+    }
+    else {
+      $row['mode'] = $mode;
+    }
+
+    return $row + parent::buildRow($entity);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function render() {
+    $entities = $this->load();
+    // If there are less than 2 gateways, disable dragging.
+    if (count($entities) <= 1) {
+      unset($this->weightKey);
+    }
+    return parent::render();
+  }
+
+}
diff --git a/modules/payment/src/PaymentGatewayManager.php b/modules/payment/src/PaymentGatewayManager.php
new file mode 100644
index 0000000..494916c
--- /dev/null
+++ b/modules/payment/src/PaymentGatewayManager.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\DefaultPluginManager;
+
+/**
+ * Manages discovery and instantiation of payment gateway plugins.
+ *
+ * @see \Drupal\commerce_payment\Annotation\CommercePaymentGateway
+ * @see plugin_api
+ */
+class PaymentGatewayManager extends DefaultPluginManager {
+
+  /**
+   * Constructs a new PaymentGatewayManager object.
+   *
+   * @param \Traversable $namespaces
+   *   An object that implements \Traversable which contains the root paths
+   *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   The cache backend.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
+   */
+  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+    parent::__construct('Plugin/Commerce/PaymentGateway', $namespaces, $module_handler, 'Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\PaymentGatewayInterface', 'Drupal\commerce_payment\Annotation\CommercePaymentGateway');
+
+    $this->alterInfo('commerce_payment_gateway_info');
+    $this->setCacheBackend($cache_backend, 'commerce_payment_gateway_plugins');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processDefinition(&$definition, $plugin_id) {
+    parent::processDefinition($definition, $plugin_id);
+
+    foreach (['id', 'label', 'display_label'] as $required_property) {
+      if (empty($definition[$required_property])) {
+        throw new PluginException(sprintf('The payment gateway %s must define the %s property.', $plugin_id, $required_property));
+      }
+    }
+  }
+
+}
diff --git a/modules/payment/src/PaymentGatewayPluginCollection.php b/modules/payment/src/PaymentGatewayPluginCollection.php
new file mode 100644
index 0000000..530a13c
--- /dev/null
+++ b/modules/payment/src/PaymentGatewayPluginCollection.php
@@ -0,0 +1,60 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Component\Plugin\PluginManagerInterface;
+use Drupal\Core\Plugin\DefaultSingleLazyPluginCollection;
+
+/**
+ * A collection of payment gateway plugins.
+ */
+class PaymentGatewayPluginCollection extends DefaultSingleLazyPluginCollection {
+
+  /**
+   * The payment gateway entity ID this plugin collection belongs to.
+   *
+   * @var string
+   */
+  protected $entityId;
+
+  /**
+   * Constructs a new PaymentGatewayPluginCollection object.
+   *
+   * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
+   *   The manager to be used for instantiating plugins.
+   * @param string $instance_id
+   *   The ID of the plugin instance.
+   * @param array $configuration
+   *   An array of configuration.
+   * @param string $entity_id
+   *   The payment gateway entity ID this plugin collection belongs to.
+   */
+  public function __construct(PluginManagerInterface $manager, $instance_id, array $configuration, $entity_id) {
+    parent::__construct($manager, $instance_id, $configuration);
+
+    $this->entityId = $entity_id;
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * @return \Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\PaymentGatewayInterface
+   *   The payment gateway plugin.
+   */
+  public function &get($instance_id) {
+    return parent::get($instance_id);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function initializePlugin($instance_id) {
+    if (!$instance_id) {
+      throw new PluginException("The payment gateway '{$this->entityId}' did not specify a plugin.");
+    }
+
+    parent::initializePlugin($instance_id);
+  }
+
+}
diff --git a/modules/payment/src/PaymentMethodStorage.php b/modules/payment/src/PaymentMethodStorage.php
new file mode 100644
index 0000000..2d47577
--- /dev/null
+++ b/modules/payment/src/PaymentMethodStorage.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\commerce\CommerceContentEntityStorage;
+use Drupal\commerce_payment\Entity\PaymentGatewayInterface;
+use Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\SupportsStoredPaymentMethods;
+use Drupal\Core\Entity\EntityStorageException;
+use Drupal\user\UserInterface;
+
+/**
+ * Defines the payment method storage.
+ */
+class PaymentMethodStorage extends CommerceContentEntityStorage implements PaymentMethodStorageInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function loadReusable(UserInterface $account, PaymentGatewayInterface $payment_gateway) {
+    if (!($payment_gateway instanceof SupportsStoredPaymentMethods)) {
+      return [];
+    }
+
+    $query = $this->getQuery()
+      ->condition('uid', $account->id())
+      ->condition('payment_gateway', $payment_gateway->id())
+      ->condition('reusable', TRUE)
+      ->sort('created', 'DESC');
+    $result = $query->execute();
+    if (empty($result)) {
+      return [];
+    }
+
+    return $this->loadMultiple($result);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doCreate(array $values) {
+    if (!isset($values['payment_gateway'])) {
+      throw new EntityStorageException('Missing "payment_gateway" property when creating a payment method.');
+    }
+
+    return parent::doCreate($values);
+  }
+
+}
diff --git a/modules/payment/src/PaymentMethodStorageInterface.php b/modules/payment/src/PaymentMethodStorageInterface.php
new file mode 100644
index 0000000..87832e6
--- /dev/null
+++ b/modules/payment/src/PaymentMethodStorageInterface.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\commerce_payment\Entity\PaymentGatewayInterface;
+use Drupal\user\UserInterface;
+
+/**
+ * Defines the interface for payment method storage.
+ */
+interface PaymentMethodStorageInterface {
+
+  /**
+   * Loads the user's reusable payment methods for the given payment gateway.
+   *
+   * @param \Drupal\user\UserInterface $account
+   *   The user account.
+   * @param \Drupal\commerce_payment\Entity\PaymentGatewayInterface $payment_gateway
+   *   The payment gateway.
+   *
+   * @return \Drupal\commerce_payment\Entity\PaymentMethodInterface[]
+   *   The reusable payment methods.
+   */
+  public function loadReusable(UserInterface $account, PaymentGatewayInterface $payment_gateway);
+
+}
diff --git a/modules/payment/src/PaymentMethodTypeManager.php b/modules/payment/src/PaymentMethodTypeManager.php
new file mode 100644
index 0000000..8863c62
--- /dev/null
+++ b/modules/payment/src/PaymentMethodTypeManager.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\DefaultPluginManager;
+
+/**
+ * Manages discovery and instantiation of payment method type plugins.
+ *
+ * @see \Drupal\commerce_payment\Annotation\CommercePaymentMethodType
+ * @see plugin_api
+ */
+class PaymentMethodTypeManager extends DefaultPluginManager {
+
+  /**
+   * Constructs a new PaymentMethodTypeManager object.
+   *
+   * @param \Traversable $namespaces
+   *   An object that implements \Traversable which contains the root paths
+   *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   The cache backend.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
+   */
+  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+    parent::__construct('Plugin/Commerce/PaymentMethodType', $namespaces, $module_handler, 'Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType\PaymentMethodTypeInterface', 'Drupal\commerce_payment\Annotation\CommercePaymentMethodType');
+
+    $this->alterInfo('commerce_payment_method_type_info');
+    $this->setCacheBackend($cache_backend, 'commerce_payment_method_type_plugins');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processDefinition(&$definition, $plugin_id) {
+    parent::processDefinition($definition, $plugin_id);
+
+    foreach (['id', 'label', 'create_label'] as $required_property) {
+      if (empty($definition[$required_property])) {
+        throw new PluginException(sprintf('The payment method type %s must define the %s property.', $plugin_id, $required_property));
+      }
+    }
+  }
+
+}
diff --git a/modules/payment/src/PaymentStorage.php b/modules/payment/src/PaymentStorage.php
new file mode 100644
index 0000000..864989b
--- /dev/null
+++ b/modules/payment/src/PaymentStorage.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\commerce\CommerceContentEntityStorage;
+use Drupal\Core\Entity\EntityStorageException;
+
+/**
+ * Defines the payment storage.
+ */
+class PaymentStorage extends CommerceContentEntityStorage {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doCreate(array $values) {
+    if (!isset($values['payment_gateway'])) {
+      throw new EntityStorageException('Missing "payment_gateway" property when creating a payment.');
+    }
+
+    return parent::doCreate($values);
+  }
+
+}
diff --git a/modules/payment/src/PaymentTypeManager.php b/modules/payment/src/PaymentTypeManager.php
new file mode 100644
index 0000000..b0a1ad1
--- /dev/null
+++ b/modules/payment/src/PaymentTypeManager.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Drupal\commerce_payment;
+
+use Drupal\Component\Plugin\Exception\PluginException;
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\DefaultPluginManager;
+
+/**
+ * Manages discovery and instantiation of payment type plugins.
+ *
+ * @see \Drupal\commerce_payment\Annotation\CommercePaymentType
+ * @see plugin_api
+ */
+class PaymentTypeManager extends DefaultPluginManager {
+
+  /**
+   * Constructs a new PaymentTypeManager object.
+   *
+   * @param \Traversable $namespaces
+   *   An object that implements \Traversable which contains the root paths
+   *   keyed by the corresponding namespace to look for plugin implementations.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
+   *   The cache backend.
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
+   *   The module handler.
+   */
+  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
+    parent::__construct('Plugin/Commerce/PaymentType', $namespaces, $module_handler, 'Drupal\commerce_payment\Plugin\Commerce\PaymentType\PaymentTypeInterface', 'Drupal\commerce_payment\Annotation\CommercePaymentType');
+
+    $this->alterInfo('commerce_payment_type_info');
+    $this->setCacheBackend($cache_backend, 'commerce_payment_type_plugins');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processDefinition(&$definition, $plugin_id) {
+    parent::processDefinition($definition, $plugin_id);
+
+    foreach (['id', 'label'] as $required_property) {
+      if (empty($definition[$required_property])) {
+        throw new PluginException(sprintf('The payment type %s must define the %s property.', $plugin_id, $required_property));
+      }
+    }
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/CheckoutPane/PaymentInformation.php b/modules/payment/src/Plugin/Commerce/CheckoutPane/PaymentInformation.php
new file mode 100644
index 0000000..516c307
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/CheckoutPane/PaymentInformation.php
@@ -0,0 +1,162 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\CheckoutPane;
+
+use Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\CheckoutFlowInterface;
+use Drupal\commerce_checkout\Plugin\Commerce\CheckoutPane\CheckoutPaneBase;
+use Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\SupportsStoredPaymentMethods;
+use Drupal\Core\Entity\Entity\EntityFormDisplay;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Render\RendererInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides the payment information pane.
+ *
+ * @CommerceCheckoutPane(
+ *   id = "payment_information",
+ *   label = @Translation("Payment information"),
+ *   default_step = "order_information",
+ *   wrapper_element = "fieldset",
+ * )
+ */
+class PaymentInformation extends CheckoutPaneBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * The renderer.
+   *
+   * @var \Drupal\Core\Render\RendererInterface
+   */
+  protected $renderer;
+
+  /**
+   * Constructs a new BillingInformation object.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\commerce_checkout\Plugin\Commerce\CheckoutFlow\CheckoutFlowInterface $checkout_flow
+   *   The parent checkout flow.
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   * @param \Drupal\Core\Render\RendererInterface $renderer
+   *   The renderer.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, CheckoutFlowInterface $checkout_flow, EntityTypeManagerInterface $entity_type_manager, RendererInterface $renderer) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition, $checkout_flow);
+
+    $this->entityTypeManager = $entity_type_manager;
+    $this->renderer = $renderer;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition, CheckoutFlowInterface $checkout_flow = NULL) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $checkout_flow,
+      $container->get('entity_type.manager'),
+      $container->get('renderer')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildPaneSummary() {
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface $payment_gateway */
+    $payment_gateway = $this->order->payment_gateway;
+    if (!$payment_gateway) {
+      return '';
+    }
+
+    $payment_method = $this->order->payment_method;
+    if ($payment_gateway instanceof SupportsStoredPaymentMethods && $payment_method) {
+      $view_builder = $this->entityTypeManager->getViewBuilder('commerce_payment_method');
+      $payment_method_view = $view_builder->view($payment_method, 'default');
+      $summary = $this->renderer->render($payment_method_view);
+    }
+    else {
+      $billing_profile = $this->order->getBillingProfile();
+      $profile_view_builder = $this->entityTypeManager->getViewBuilder('profile');
+      $profile_view = $profile_view_builder->view($billing_profile, 'default');
+      $summary = $payment_gateway->getPlugin()->getDisplayLabel();
+      $summary .= $this->renderer->render($profile_view);
+    }
+
+    return $summary;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildPaneForm(array $pane_form, FormStateInterface $form_state, array &$complete_form) {
+    $payment_gateway_storage = $this->entityTypeManager->getStorage('commerce_payment_method');
+    /** @var \Drupal\commerce_payment\PaymentMethodStorageInterface $payment_method_storage */
+    $payment_method_storage = $this->entityTypeManager->getStorage('commerce_payment_method');
+    /** @var \Drupal\commerce_payment\Entity\PaymentGatewayInterface[] $payment_gateways */
+    $payment_gateways = $payment_gateway_storage->loadMultiple();
+
+    $options = [];
+    $default_option = NULL;
+    $owner = $this->order->getOwner();
+    foreach ($payment_gateways as $payment_gateway) {
+      if ($owner) {
+        $payment_methods = $payment_method_storage->loadReusable($owner, $payment_gateway);
+        foreach ($payment_methods as $payment_method) {
+          $options[$payment_method->id()] = $payment_method->label();
+        }
+      }
+      $payment_method_types = $payment_gateway->getPlugin()->getPaymentMethodTypes();
+      foreach ($payment_method_types as $payment_method_type) {
+        $options['new'] = $payment_method_type->getCreateLabel();
+      }
+    }
+
+    $pane_form['payment_method'] = [
+      '#type' => 'radios',
+      '#title' => $this->t('Payment method'),
+      '#options' => $options,
+      '#default_value' => $default_option,
+    ];
+    $payment_method = $payment_method_storage->create([
+      'type' => 'credit_card',
+      'payment_gateway' => $payment_gateway->id(),
+      'uid' => $this->order->getOwnerId(),
+    ]);
+    $plugin_form = $payment_gateway->getForm('add-payment-method');
+    $pane_form['add'] = $plugin_form->buildForm($pane_form['add'], $form_state, $payment_method);
+
+    return $pane_form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validatePaneForm(array &$pane_form, FormStateInterface $form_state, array &$complete_form) {
+
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitPaneForm(array &$pane_form, FormStateInterface $form_state, array &$complete_form) {
+
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/Form/PaymentMethodAddForm.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/Form/PaymentMethodAddForm.php
new file mode 100644
index 0000000..e802ed7
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/Form/PaymentMethodAddForm.php
@@ -0,0 +1,51 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway\Form;
+
+class PaymentMethodAddForm {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildPluginForm(array $plugin_form, FormStateInterface $form_state) {
+    $plugin_form['payment_details'] = [
+      '#type' => 'container',
+    ];
+    $plugin_form['billing_information'] = [
+      '#type' => 'inline_entity_form',
+      '#entity_type' => 'profile',
+      '#bundle' => 'billing',
+      //'#default_value' => $payment_method->getBillingProfile(),
+      '#save_entity' => FALSE,
+    ];
+    // @todo Needs to be moved to a #process, or a widget setting.
+    // Remove the details wrapper from the address field.
+    //if (!empty($plugin_form['address']['widget'][0])) {
+    //  $plugin_form['address']['widget'][0]['#type'] = 'container';
+    //}
+
+    return $plugin_form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validatePluginForm(array &$plugin_form, FormStateInterface $form_state, array &$complete_form) {
+    $billing_profile = clone $plugin_form['#billing_profile'];
+    $form_display = EntityFormDisplay::collectRenderDisplay($billing_profile, 'default');
+    $form_display->extractFormValues($billing_profile, $plugin_form, $form_state);
+    $form_display->validateFormValues($billing_profile, $plugin_form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitPluginForm(array &$plugin_form, FormStateInterface $form_state, array &$complete_form) {
+    $billing_profile = clone $plugin_form['#billing_profile'];
+    $form_display = EntityFormDisplay::collectRenderDisplay($billing_profile, 'default');
+    $form_display->extractFormValues($billing_profile, $plugin_form, $form_state);
+    $billing_profile->save();
+    $this->order->setBillingProfile($billing_profile);
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/Form/PaymentMethodEditForm.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/Form/PaymentMethodEditForm.php
new file mode 100644
index 0000000..e69de29
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/OnsitePaymentGatewayBase.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/OnsitePaymentGatewayBase.php
new file mode 100644
index 0000000..37a7445
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/OnsitePaymentGatewayBase.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+/**
+ * Provides the base class for onsite payment gateways.
+ */
+abstract class OnsitePaymentGatewayBase extends PaymentGatewayBase {
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/OnsitePaymentGatewayInterface.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/OnsitePaymentGatewayInterface.php
new file mode 100644
index 0000000..4ad0438
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/OnsitePaymentGatewayInterface.php
@@ -0,0 +1,9 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+/**
+ * Defines the base interface for onsite payment gateways.
+ */
+interface OnsitePaymentGatewayInterface extends PaymentGatewayInterface, SupportsStoredPaymentMethods {
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/PaymentGatewayBase.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/PaymentGatewayBase.php
new file mode 100644
index 0000000..a19f46b
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/PaymentGatewayBase.php
@@ -0,0 +1,217 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+use Drupal\commerce_payment\PaymentMethodTypeManager;
+use Drupal\commerce_payment\PaymentTypeManager;
+use Drupal\Component\Utility\NestedArray;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Plugin\PluginBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides the base class for payment gateways.
+ */
+abstract class PaymentGatewayBase extends PluginBase implements PaymentGatewayInterface, ContainerFactoryPluginInterface {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * The payment type used by the gateway.
+   *
+   * @var \Drupal\commerce_payment\Plugin\Commerce\PaymentType\PaymentTypeInterface
+   */
+  protected $paymentType;
+
+  /**
+   * The payment method types handled by the gateway.
+   *
+   * @var \Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType\PaymentMethodTypeInterface[]
+   */
+  protected $paymentMethodTypes;
+
+  /**
+   * Constructs a new PaymentGatewayBase object.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   * @param \Drupal\commerce_payment\PaymentTypeManager $payment_type_manager
+   *   The payment type manager.
+   * @param \Drupal\commerce_payment\PaymentMethodTypeManager $payment_method_type_manager
+   *   The payment method type manager.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, EntityTypeManagerInterface $entity_type_manager, PaymentTypeManager $payment_type_manager, PaymentMethodTypeManager $payment_method_type_manager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+
+    $this->entityTypeManager = $entity_type_manager;
+    // Instantiate the types right away to ensure that their IDs are valid.
+    $this->paymentType = $payment_type_manager->createInstance($this->pluginDefinition['payment_type']);
+    foreach ($this->pluginDefinition['payment_method_types'] as $plugin_id) {
+      $this->paymentMethodTypes[$plugin_id] = $payment_method_type_manager->createInstance($plugin_id);
+    }
+    $this->setConfiguration($configuration);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('entity_type.manager'),
+      $container->get('plugin.manager.commerce_payment_type'),
+      $container->get('plugin.manager.commerce_payment_method_type')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getLabel() {
+    return $this->pluginDefinition['label'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getDisplayLabel() {
+    return $this->configuration['display_label'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentType() {
+    return $this->paymentType;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPaymentMethodTypes() {
+    // Filter out payment method types disabled by the merchant.
+    return array_intersect_key($this->paymentMethodTypes, array_flip($this->configuration['payment_method_types']));
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMode() {
+    return $this->configuration['mode'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getSupportedModes() {
+    return $this->pluginDefinition['modes'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    return [];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getConfiguration() {
+    return $this->configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setConfiguration(array $configuration) {
+    $this->configuration = NestedArray::mergeDeep($this->defaultConfiguration(), $configuration);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultConfiguration() {
+    $modes = array_keys($this->getSupportedModes());
+
+    return [
+      'mode' => $modes ? reset($modes) : '',
+      'payment_method_types' => [],
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $modes = $this->getSupportedModes();
+    $payment_method_types = array_map(function ($payment_method_type) {
+      return $payment_method_type->getLabel();
+    }, $this->paymentMethodTypes);
+
+    $form['mode'] = [
+      '#type' => 'radios',
+      '#title' => $this->t('Mode'),
+      '#options' => $modes,
+      '#default_value' => $this->configuration['mode'],
+      '#required' => TRUE,
+      '#access' => !empty($modes),
+    ];
+    $form['payment_method_types'] = [
+      '#type' => 'checkboxes',
+      '#title' => $this->t('Payment method types'),
+      '#options' => $payment_method_types,
+      '#default_value' => $this->configuration['payment_method_types'],
+      '#required' => TRUE,
+      '#access' => count($payment_method_types) > 1,
+    ];
+
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {}
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+    if (!$form_state->getErrors()) {
+      $values = $form_state->getValue($form['#parents']);
+      $values['payment_method_types'] = array_filter($values['payment_method_types']);
+
+      $this->configuration['mode'] = $values['mode'];
+      $this->configuration['payment_method_types'] = array_keys($values['payment_method_types']);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getForm($form_id) {
+    $forms = $this->pluginDefinition['forms'];
+    if (empty($forms[$form_id])) {
+      throw new \InvalidArgumentException(sprintf('Invalid form "%s" requested for plugin "%s"', $form_id, $this->getPluginId()));
+    }
+
+    return new $forms[$form_id]($this);
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/PaymentGatewayInterface.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/PaymentGatewayInterface.php
new file mode 100644
index 0000000..bc42a0f
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/PaymentGatewayInterface.php
@@ -0,0 +1,79 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+use Drupal\Component\Plugin\ConfigurablePluginInterface;
+use Drupal\Component\Plugin\DerivativeInspectionInterface;
+use Drupal\Component\Plugin\PluginInspectionInterface;
+use Drupal\Core\Plugin\PluginFormInterface;
+
+/**
+ * Defines the base interface for payment gateways.
+ */
+interface PaymentGatewayInterface extends ConfigurablePluginInterface, PluginFormInterface, PluginInspectionInterface, DerivativeInspectionInterface {
+
+  /**
+   * Gets the payment gateway label.
+   *
+   * The label is admin-facing and usually includes the name of the used API.
+   * For example: "Braintree (Hosted Fields)".
+   *
+   * @return mixed
+   *   The payment gateway label.
+   */
+  public function getLabel();
+
+  /**
+   * Gets the payment gateway display label.
+   *
+   * The display label is customer-facing and more generic.
+   * For example: "Braintree".
+   *
+   * @return string
+   *   The payment gateway display label.
+   */
+  public function getDisplayLabel();
+
+  /**
+   * Gets the mode in which the payment gateway is operating.
+   *
+   * @return string
+   *   The machine name of the mode.
+   */
+  public function getMode();
+
+  /**
+   * Gets the supported modes.
+   *
+   * @return string[]
+   *   The mode labels keyed by machine name.
+   */
+  public function getSupportedModes();
+
+  /**
+   * Gets the payment type used by the payment gateway.
+   *
+   * @return \Drupal\commerce_payment\Plugin\Commerce\PaymentType\PaymentTypeInterface
+   *   The payment type.
+   */
+  public function getPaymentType();
+
+  /**
+   * Gets the payment method types handled by the payment gateway.
+   *
+   * @return \Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType\PaymentMethodTypeInterface[]
+   *   The payment method types.
+   */
+  public function getPaymentMethodTypes();
+
+  /**
+   * Gets the plugin form with the given ID.
+   *
+   * @param string $form_id
+   *   The form ID.
+   *
+   * @return \Drupal\commerce\Plugin\PluginFormInterface
+   */
+  public function getForm($form_id);
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsAuthorizations.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsAuthorizations.php
new file mode 100644
index 0000000..d0a87dd
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsAuthorizations.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+use Drupal\commerce_order\Entity\OrderInterface;
+use Drupal\commerce_payment\Entity\PaymentInterface;
+use Drupal\commerce_payment\Entity\PaymentMethodInterface;
+use Drupal\commerce_price\Price;
+
+/**
+ * Defines the interface for gateways which support authorizing payments.
+ */
+interface SupportsAuthorizations {
+
+  /**
+   * Creates and authorizes a payment with the given amount.
+   *
+   * @param \Drupal\commerce_price\Price $amount
+   *   The amount to authorize.
+   * @param \Drupal\commerce_payment\Entity\PaymentMethodInterface $payment_method
+   *   The payment method, if known.
+   * @param \Drupal\commerce_order\Entity\OrderInterface $order
+   *   The parent order.
+   */
+  public function authorize(Price $amount, PaymentMethodInterface $payment_method = NULL, OrderInterface $order);
+
+  /**
+   * Captures the given payment.
+   *
+   * Only payments in the 'authorization' state can be captured.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentInterface $payment
+   *   The payment to capture.
+   * @param \Drupal\commerce_price\Price $amount
+   *   The amount to capture. If NULL, defaults to the entire payment amount.
+   */
+  public function capture(PaymentInterface $payment, Price $amount = NULL);
+
+  /**
+   * Voids the given payment.
+   *
+   * Only payments in the 'authorization' state can be voided.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentInterface $payment
+   *   The payment to void.
+   */
+  public function void(PaymentInterface $payment);
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsRefunds.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsRefunds.php
new file mode 100644
index 0000000..2a11df2
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsRefunds.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+use Drupal\commerce_payment\Entity\PaymentInterface;
+use Drupal\commerce_price\Price;
+
+/**
+ * Defines the interface for gateways which support refunds.
+ */
+interface SupportsRefunds {
+
+  /**
+   * Refunds the given payment.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentInterface $payment
+   *   The payment to refund.
+   * @param \Drupal\commerce_price\Price $amount
+   *   The amount to refund. If NULL, defaults to the entire payment amount.
+   */
+  public function refund(PaymentInterface $payment, Price $amount = NULL);
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsStoredPaymentMethods.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsStoredPaymentMethods.php
new file mode 100644
index 0000000..184aafa
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsStoredPaymentMethods.php
@@ -0,0 +1,32 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+use Drupal\commerce_payment\Entity\PaymentMethodInterface;
+
+/**
+ * Defines the interface for gateways which support storing payment methods.
+ */
+interface SupportsStoredPaymentMethods {
+
+  /**
+   * Creates a payment method with the given payment details.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentMethodInterface $payment_method
+   *   The payment method.
+   * @param array $payment_details
+   *   The gateway-specific payment details.
+   */
+  public function createPaymentMethod(PaymentMethodInterface $payment_method, array $payment_details);
+
+  /**
+   * Deletes the given payment method.
+   *
+   * Both the entity and the remote record are deleted.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentMethodInterface $payment_method
+   *   The payment method.
+   */
+  public function deletePaymentMethod(PaymentMethodInterface $payment_method);
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsUpdatingStoredPaymentMethods.php b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsUpdatingStoredPaymentMethods.php
new file mode 100644
index 0000000..b1787ed
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentGateway/SupportsUpdatingStoredPaymentMethods.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentGateway;
+
+use Drupal\commerce_payment\Entity\PaymentMethodInterface;
+
+/**
+ * Defines the interface for gateways which support updating stored payment methods.
+ */
+interface SupportsUpdatingStoredPaymentMethods {
+
+  /**
+   * Updates the given payment.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentMethodInterface $payment_method
+   *   The payment method.
+   */
+  public function updatePaymentMethod(PaymentMethodInterface $payment_method);
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentMethodType/CreditCard.php b/modules/payment/src/Plugin/Commerce/PaymentMethodType/CreditCard.php
new file mode 100644
index 0000000..48b13b5
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentMethodType/CreditCard.php
@@ -0,0 +1,64 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType;
+
+use Drupal\commerce\BundleFieldDefinition;
+use Drupal\commerce_payment\CreditCard as CreditCardHelper;
+use Drupal\commerce_payment\Entity\PaymentMethodInterface;
+
+/**
+ * Provides the credit card payment method type.
+ *
+ * @CommercePaymentMethodType(
+ *   id = "credit_card",
+ *   label = @Translation("Credit card"),
+ *   create_label = @Translation("New credit card"),
+ * )
+ */
+class CreditCard extends PaymentMethodTypeBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildLabel(PaymentMethodInterface $payment_method) {
+    $card_type = CreditCardHelper::getType($payment_method->card_type->value);
+    $args = [
+      '@card_type' => $card_type->getLabel(),
+      '@card_number' => $payment_method->card_number->value,
+    ];
+    return $this->t('@card_type ending in @card_number', $args);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildFieldDefinitions() {
+    $fields = parent::buildFieldDefinitions();
+
+    $fields['card_type'] = BundleFieldDefinition::create('list_string')
+      ->setLabel(t('Card type'))
+      ->setDescription(t('The credit card type.'))
+      ->setRequired(TRUE)
+      ->setSetting('allowed_values_function', ['\Drupal\commerce_payment\CreditCard', 'getTypeLabels']);
+
+    $fields['card_number'] = BundleFieldDefinition::create('string')
+      ->setLabel(t('Card number'))
+      ->setDescription(t('The last 4 digits of the credit card number'))
+      ->setRequired(TRUE);
+
+    $fields['card_exp_month'] = BundleFieldDefinition::create('integer')
+      ->setLabel(t('Card expiration month'))
+      ->setDescription(t('The credit card expiration month.'))
+      ->setRequired(TRUE)
+      ->setSetting('size', 'tiny');
+
+    $fields['card_exp_year'] = BundleFieldDefinition::create('integer')
+      ->setLabel(t('Card expiration year'))
+      ->setDescription(t('The credit card expiration year.'))
+      ->setRequired(TRUE)
+      ->setSetting('size', 'tiny');
+
+    return $fields;
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentMethodType/PayPal.php b/modules/payment/src/Plugin/Commerce/PaymentMethodType/PayPal.php
new file mode 100644
index 0000000..72dc8c7
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentMethodType/PayPal.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType;
+
+use Drupal\commerce\BundleFieldDefinition;
+use Drupal\commerce_payment\Entity\PaymentMethodInterface;
+
+/**
+ * Provides the PayPal payment method type.
+ *
+ * @CommercePaymentMethodType(
+ *   id = "paypal",
+ *   label = @Translation("PayPal account"),
+ *   create_label = @Translation("New PayPal account"),
+ * )
+ */
+class PayPal extends PaymentMethodTypeBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildLabel(PaymentMethodInterface $payment_method) {
+    $args = [
+      '@paypal_mail' => $payment_method->paypal_mail->value,
+    ];
+    return $this->t('PayPal account (@paypal_mail)', $args);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildFieldDefinitions() {
+    $fields = parent::buildFieldDefinitions();
+
+    $fields['paypal_mail'] = BundleFieldDefinition::create('email')
+      ->setLabel(t('PayPal Email'))
+      ->setDescription(t('The email address associated with the PayPal account.'))
+      ->setRequired(TRUE);
+
+    return $fields;
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentMethodType/PaymentMethodTypeBase.php b/modules/payment/src/Plugin/Commerce/PaymentMethodType/PaymentMethodTypeBase.php
new file mode 100644
index 0000000..140864a
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentMethodType/PaymentMethodTypeBase.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType;
+
+use Drupal\Core\Plugin\PluginBase;
+
+/**
+ * Provides the base payment method type class.
+ */
+abstract class PaymentMethodTypeBase extends PluginBase implements PaymentMethodTypeInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getLabel() {
+    return $this->pluginDefinition['label'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCreateLabel() {
+    return $this->pluginDefinition['create_label'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildFieldDefinitions() {
+    return [];
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentMethodType/PaymentMethodTypeInterface.php b/modules/payment/src/Plugin/Commerce/PaymentMethodType/PaymentMethodTypeInterface.php
new file mode 100644
index 0000000..3ffc5ad
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentMethodType/PaymentMethodTypeInterface.php
@@ -0,0 +1,40 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentMethodType;
+
+use Drupal\commerce\BundlePluginInterface;
+use Drupal\commerce_payment\Entity\PaymentMethodInterface;
+
+/**
+ * Defines the interface for payment method types.
+ */
+interface PaymentMethodTypeInterface extends BundlePluginInterface {
+
+  /**
+   * Gets the payment method type label.
+   *
+   * @return string
+   *   The payment method type label.
+   */
+  public function getLabel();
+
+  /**
+   * Gets the payment method type create label.
+   *
+   * @return string
+   *   The payment method type create label.
+   */
+  public function getCreateLabel();
+
+  /**
+   * Builds a label for the given payment method.
+   *
+   * @param \Drupal\commerce_payment\Entity\PaymentMethodInterface $payment_method
+   *   The payment method.
+   *
+   * @return string
+   *   The label.
+   */
+  public function buildLabel(PaymentMethodInterface $payment_method);
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentType/PaymentDefault.php b/modules/payment/src/Plugin/Commerce/PaymentType/PaymentDefault.php
new file mode 100644
index 0000000..4688ae1
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentType/PaymentDefault.php
@@ -0,0 +1,22 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentType;
+
+/**
+ * Provides the default payment type.
+ *
+ * @CommercePaymentType(
+ *   id = "payment_default",
+ *   label = @Translation("Default"),
+ * )
+ */
+class PaymentDefault extends PaymentTypeBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildFieldDefinitions() {
+    return [];
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentType/PaymentTypeBase.php b/modules/payment/src/Plugin/Commerce/PaymentType/PaymentTypeBase.php
new file mode 100644
index 0000000..331246d
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentType/PaymentTypeBase.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentType;
+
+use Drupal\Core\Plugin\PluginBase;
+
+/**
+ * Provides the base payment type class.
+ */
+abstract class PaymentTypeBase extends PluginBase implements PaymentTypeInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getLabel() {
+    return $this->pluginDefinition['label'];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getWorkflowId() {
+    return $this->pluginDefinition['workflow'];
+  }
+
+}
diff --git a/modules/payment/src/Plugin/Commerce/PaymentType/PaymentTypeInterface.php b/modules/payment/src/Plugin/Commerce/PaymentType/PaymentTypeInterface.php
new file mode 100644
index 0000000..259f40e
--- /dev/null
+++ b/modules/payment/src/Plugin/Commerce/PaymentType/PaymentTypeInterface.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace Drupal\commerce_payment\Plugin\Commerce\PaymentType;
+
+use Drupal\commerce\BundlePluginInterface;
+
+/**
+ * Defines the interface for payment types.
+ */
+interface PaymentTypeInterface extends BundlePluginInterface {
+
+  /**
+   * Gets the payment type label.
+   *
+   * @return string
+   *   The payment type label.
+   */
+  public function getLabel();
+
+  /**
+   * Gets the payment workflow ID.
+   *
+   * @return string
+   *   The payment workflow ID.
+   */
+  public function getWorkflowId();
+
+}