diff --git a/modules/mollie_customers/mollie_customers.info.yml b/modules/mollie_customers/mollie_customers.info.yml
new file mode 100644
index 0000000..a054ea4
--- /dev/null
+++ b/modules/mollie_customers/mollie_customers.info.yml
@@ -0,0 +1,11 @@
+name: Mollie Customers
+description: Customers integration for Mollie.
+package: Mollie for Drupal
+
+type: module
+core: 8.x
+
+php: 7.0
+
+dependencies:
+  - mollie:mollie
diff --git a/modules/mollie_customers/mollie_customers.links.action.yml b/modules/mollie_customers/mollie_customers.links.action.yml
new file mode 100644
index 0000000..0b47f9e
--- /dev/null
+++ b/modules/mollie_customers/mollie_customers.links.action.yml
@@ -0,0 +1,11 @@
+entity.mollie_customer.add_form:
+  route_name: entity.mollie_customer.add_form
+  title: 'Add Mollie customer'
+  appears_on:
+    - entity.mollie_customer.collection
+
+entity.mollie_customer.delete_form:
+  route_name: entity.mollie_customer.delete_form
+  title: 'Delete'
+  appears_on:
+    - entity.mollie_customer.collection
diff --git a/modules/mollie_customers/mollie_customers.links.menu.yml b/modules/mollie_customers/mollie_customers.links.menu.yml
new file mode 100644
index 0000000..d449285
--- /dev/null
+++ b/modules/mollie_customers/mollie_customers.links.menu.yml
@@ -0,0 +1,5 @@
+entity.mollie_customers.collection:
+  title: 'Customers'
+  description: 'Manage customers made through Mollie for Drupal.'
+  parent: mollie.admin
+  route_name: entity.mollie_customer.collection
diff --git a/modules/mollie_customers/mollie_customers.links.task.yml b/modules/mollie_customers/mollie_customers.links.task.yml
new file mode 100644
index 0000000..9b62a77
--- /dev/null
+++ b/modules/mollie_customers/mollie_customers.links.task.yml
@@ -0,0 +1,15 @@
+entity.mollie_customers.collection:
+  title: 'Mollie customers'
+  route_name: entity.mollie_customers.collection
+  base_route: entity.mollie_customers.collection
+
+entity.mollie_customers.canonical:
+  route_name: entity.mollie_customers.canonical
+  base_route: entity.mollie_customers.canonical
+  title: View
+
+entity.mollie_customers.delete_form:
+  route_name:  entity.mollie_customers.delete_form
+  base_route:  entity.mollie_customers.canonical
+  title: Delete
+  weight: 10
diff --git a/modules/mollie_customers/mollie_customers.permissions.yml b/modules/mollie_customers/mollie_customers.permissions.yml
new file mode 100644
index 0000000..de8fcf5
--- /dev/null
+++ b/modules/mollie_customers/mollie_customers.permissions.yml
@@ -0,0 +1,6 @@
+'access mollie customers overview':
+  title: 'Access Mollie for Drupal customers overview'
+  restrict access: TRUE
+
+permission_callbacks:
+  - Drupal\mollie_customers\CustomerPermissions::customerPermissions
diff --git a/modules/mollie_customers/mollie_customers.routing.yml b/modules/mollie_customers/mollie_customers.routing.yml
new file mode 100644
index 0000000..80676df
--- /dev/null
+++ b/modules/mollie_customers/mollie_customers.routing.yml
@@ -0,0 +1,32 @@
+entity.mollie_customer.collection:
+  path: '/admin/mollie/customers'
+  defaults:
+    _entity_list: 'mollie_customer'
+    _title: 'Mollie customers'
+  requirements:
+    _permission: 'access mollie customers overview'
+
+entity.mollie_customer.canonical:
+  path: '/mollie/customer/{mollie_customer}'
+  defaults:
+    _entity_view: 'mollie_customer'
+    _title: 'Mollie customer'
+    _title_callback: 'Drupal\mollie_customers\Controller\CustomerController::customerTitle'
+  requirements:
+    _entity_access: 'mollie_customer.view'
+
+entity.mollie_customer.add_form:
+  path: '/mollie/customer/add'
+  defaults:
+    _entity_form: mollie_customer.add
+    _title: 'Add Mollie customer'
+  requirements:
+    _entity_create_access: 'mollie_customer'
+
+entity.mollie_customer.delete_form:
+  path: '/mollie/customer/{mollie_customer}/delete'
+  defaults:
+    _entity_form: mollie_customer.delete
+    _title: 'Delete'
+  requirements:
+    _entity_access: 'mollie_customer.delete'
diff --git a/modules/mollie_customers/src/Controller/CustomerController.php b/modules/mollie_customers/src/Controller/CustomerController.php
new file mode 100644
index 0000000..f35dddf
--- /dev/null
+++ b/modules/mollie_customers/src/Controller/CustomerController.php
@@ -0,0 +1,28 @@
+<?php
+
+namespace Drupal\mollie_customers\Controller;
+
+use Drupal\mollie\Controller\MollieEntityBaseController;
+use Drupal\mollie_customers\Entity\Customer;
+
+/**
+ * Class CustomerController.
+ *
+ * @package Drupal\mollie_customers\Controller
+ */
+class CustomerController extends MollieEntityBaseController {
+
+  /**
+   * Returns the title for a customer.
+   *
+   * @param \Drupal\mollie_customers\Entity\Customer $mollie_customer
+   *   Customer.
+   *
+   * @return string
+   *   Title for the customer.
+   */
+  public function customerTitle(Customer $mollie_customer): string {
+    return $this->entityTitle($mollie_customer);
+  }
+
+}
diff --git a/modules/mollie_customers/src/Controller/CustomerListBuilder.php b/modules/mollie_customers/src/Controller/CustomerListBuilder.php
new file mode 100644
index 0000000..88053ad
--- /dev/null
+++ b/modules/mollie_customers/src/Controller/CustomerListBuilder.php
@@ -0,0 +1,102 @@
+<?php
+
+namespace Drupal\mollie_customers\Controller;
+
+use Drupal\Core\Datetime\DateFormatterInterface;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityListBuilder;
+use Drupal\Core\Entity\EntityStorageInterface;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Link;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Class CustomerListBuilder.
+ *
+ * @package Drupal\mollie_customers\Controller
+ */
+class CustomerListBuilder extends EntityListBuilder {
+
+  /**
+   * Date formatter.
+   *
+   * @var \Drupal\Core\Datetime\DateFormatterInterface
+   */
+  protected $dateFormatter;
+
+  /**
+   * Constructs a new EntityListBuilder object.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface $entityType
+   *   The entity type definition.
+   * @param \Drupal\Core\Entity\EntityStorageInterface $storage
+   *   The entity storage class.
+   * @param \Drupal\Core\Datetime\DateFormatterInterface $dateFormatter
+   *   Date formatter.
+   */
+  public function __construct(
+    EntityTypeInterface $entityType,
+    EntityStorageInterface $storage,
+    DateFormatterInterface $dateFormatter
+  ) {
+    parent::__construct($entityType, $storage);
+
+    $this->dateFormatter = $dateFormatter;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function createInstance(ContainerInterface $container, EntityTypeInterface $entityType) {
+    return new static(
+      $entityType,
+      $container->get('entity.manager')->getStorage($entityType->id()),
+      $container->get('date.formatter')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildHeader() {
+    $header = [];
+
+    $header['id'] = $this->t('Customer ID');
+    $header['mode'] = $this->t('Mode');
+    $header['name'] = $this->t('Name');
+    $header['email'] = $this->t('Email');
+    $header['created'] = $this->t('Created');
+
+    return $header + parent::buildHeader();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildRow(EntityInterface $entity) {
+    /** @var \Drupal\mollie_customers\Entity\Customer $entity */
+    $row = [];
+
+    $row['id'] = Link::fromTextAndUrl($entity->id(), $entity->toUrl());
+    $row['mode'] = $entity->getMode();
+    $row['name'] = $entity->getName();
+    $row['email'] = $entity->getEmail();
+    $row['created'] = $this->getFormattedDate($entity->getCreatedTime());
+
+    return $row + parent::buildRow($entity);
+  }
+
+  /**
+   * @param string $date
+   *   Date in ISO 8601 format.
+   *
+   * @return string
+   *   Date formatted in medium date format.
+   */
+  protected function getFormattedDate($date) {
+    $dateTime = new \DateTime($date);
+    return $this->dateFormatter
+      ->format($dateTime->format('U'), 'medium');
+  }
+
+}
diff --git a/modules/mollie_customers/src/CustomerAccessControlHandler.php b/modules/mollie_customers/src/CustomerAccessControlHandler.php
new file mode 100644
index 0000000..1f68198
--- /dev/null
+++ b/modules/mollie_customers/src/CustomerAccessControlHandler.php
@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\mollie_customers;
+
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Entity\EntityAccessControlHandler;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Session\AccountInterface;
+
+/**
+ * Class CustomerAccessControlHandler.
+ *
+ * @package Drupal\mollie_customers
+ */
+class CustomerAccessControlHandler extends EntityAccessControlHandler {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function checkAccess(EntityInterface $entity, $operation, AccountInterface $account) {
+    switch ($operation) {
+      case 'view':
+        return AccessResult::allowedIfHasPermission($account, 'view mollie_customer entity');
+
+      case 'delete':
+        return AccessResult::allowedIfHasPermission($account, 'delete mollie_customer entity');
+    }
+
+    return AccessResult::allowed();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function checkCreateAccess(AccountInterface $account, array $context, $entityBundle = NULL) {
+    return AccessResult::allowedIfHasPermission($account, 'create mollie_customer entity');
+  }
+
+}
diff --git a/modules/mollie_customers/src/CustomerInterface.php b/modules/mollie_customers/src/CustomerInterface.php
new file mode 100644
index 0000000..10ddd8a
--- /dev/null
+++ b/modules/mollie_customers/src/CustomerInterface.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace Drupal\mollie_customers;
+
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityChangedInterface;
+
+/**
+ * Interface CustomerInterface.
+ *
+ * @package Drupal\mollie_customers
+ */
+interface CustomerInterface extends ContentEntityInterface, EntityChangedInterface {
+
+  /**
+   * Returns the time the customer was created.
+   *
+   * @return string
+   *   ISO 8601 representation of the time the customer was created..
+   */
+  public function getCreatedTime(): string;
+
+  /**
+   * Returns the full name of the customer as provided when the customer was
+   * created.
+   *
+   * @return string
+   *   The name of the customer.
+   */
+  public function getName(): string;
+
+  /**
+   * Returns the email address of the customer as provided when the customer was
+   * created.
+   *
+   * @return string
+   *   The email of the customer.
+   */
+  public function getEmail(): string;
+
+  /**
+   * Returns the mode used to create this customer.
+   *
+   * @return string
+   *   Mode the customer was created in.
+   */
+  public function getMode(): string;
+
+}
diff --git a/modules/mollie_customers/src/CustomerPermissions.php b/modules/mollie_customers/src/CustomerPermissions.php
new file mode 100644
index 0000000..5182c6a
--- /dev/null
+++ b/modules/mollie_customers/src/CustomerPermissions.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\mollie_customers;
+
+use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
+use Drupal\Component\Plugin\Exception\PluginNotFoundException;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\mollie\MollieEntityBasePermissions;
+
+/**
+ * Class CustomerPermissions.
+ *
+ * @package Drupal\mollie_customers
+ */
+class CustomerPermissions extends MollieEntityBasePermissions {
+
+  /**
+   * Returns permissions for operations on mollie_customer entities.
+   *
+   * @return array
+   *   Array with permissions.
+   */
+  public function customerPermissions(): array {
+    try {
+      $entityType = $this->entityTypeManager
+        ->getStorage('mollie_customer')
+        ->getEntityType();
+      return $this->entityBasePermissions($entityType);
+    }
+    catch (InvalidPluginDefinitionException | PluginNotFoundException $e) {
+      watchdog_exception('mollie', $e);
+    }
+
+    return [];
+  }
+
+  /**
+   * Returns available operations on entities of a given type.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface $entityType
+   *   Entity type.
+   *
+   * @return array
+   *   Array with operations.
+   */
+  protected function getAvailableOperations(EntityTypeInterface $entityType): array {
+    return array_merge(parent::getAvailableOperations($entityType), ['delete']);
+  }
+
+}
diff --git a/modules/mollie_customers/src/Entity/Customer.php b/modules/mollie_customers/src/Entity/Customer.php
new file mode 100644
index 0000000..86ea894
--- /dev/null
+++ b/modules/mollie_customers/src/Entity/Customer.php
@@ -0,0 +1,164 @@
+<?php
+
+namespace Drupal\mollie_customers\Entity;
+
+use Drupal\Core\Entity\ContentEntityBase;
+use Drupal\Core\Entity\EntityChangedTrait;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Drupal\mollie_customers\CustomerInterface;
+
+/**
+ * Class Customer.
+ *
+ * @package Drupal\mollie_customers\Entity
+ *
+ * @ContentEntityType(
+ *   id = "mollie_customer",
+ *   label = @Translation("Mollie customer"),
+ *   handlers = {
+ *     "access" = "Drupal\mollie_customers\CustomerAccessControlHandler",
+ *     "form" = {
+ *       "add" = "Drupal\mollie_customers\Form\CustomerForm",
+ *       "delete" = "Drupal\mollie_customers\Form\CustomerDeleteForm",
+ *     },
+ *     "list_builder" = "Drupal\mollie_customers\Controller\CustomerListBuilder",
+ *     "view_builder" = "Drupal\Core\Entity\EntityViewBuilder",
+ *     "storage" = "Drupal\mollie_customers\Entity\CustomerStorage",
+ *   },
+ *   fieldable = FALSE,
+ *   entity_keys = {
+ *     "id" = "id",
+ *     "label" = "id",
+ *   },
+ *   links = {
+ *     "canonical" = "/admin/content/mollie/customer/{mollie_customer}",
+ *     "collection" = "/admin/content/mollie/customers",
+ *     "add-form" = "/admin/content/mollie/customer/add",
+ *     "delete-form" = "/admin/content/mollie/customer/{mollie_customer}/delete",
+ *   },
+ * )
+ */
+class Customer extends ContentEntityBase implements CustomerInterface {
+
+  use EntityChangedTrait;
+  use StringTranslationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function baseFieldDefinitions(EntityTypeInterface $entityType) {
+    $fields = [];
+
+    // Customer ID.
+    $fields['id'] = BaseFieldDefinition::create('integer')
+      ->setLabel(t('ID'))
+      ->setDescription(t('The customer’s unique identifier.'))
+      ->setReadOnly(TRUE);
+
+    // Customer created date.
+    $fields['created'] = BaseFieldDefinition::create('datetime')
+      ->setLabel(t('Created'))
+      ->setDescription(t('The customer’s date and time of creation, in ISO 8601 format.'))
+      ->setReadOnly(TRUE);
+
+    // Customer name.
+    $fields['name'] = BaseFieldDefinition::create('string')
+      ->setLabel(t('Name'))
+      ->setDescription(t('The full name of the customer as provided when the customer was created.'))
+      ->setRequired(TRUE)
+      ->setDisplayOptions(
+        'form',
+        [
+          'type' => 'string_textfield',
+          'weight' => 1,
+        ]
+      )
+      ->setDisplayOptions('view', [
+        'label' => 'inline',
+        'type' => 'string',
+        'weight' => 0,
+      ]);
+
+    // Customer email.
+    $fields['email'] = BaseFieldDefinition::create('string')
+      ->setLabel(t('Email'))
+      ->setDescription(t('The email address of the customer as provided when the customer was created.'))
+      ->setRequired(TRUE)
+      ->setDisplayOptions(
+        'form',
+        [
+          'type' => 'string_textfield',
+          'weight' => 1,
+        ]
+      )
+      ->setDisplayOptions(
+        'view',
+        [
+          'label' => 'inline',
+          'type' => 'email',
+          'weight' => 0,
+        ]
+      );
+
+    // Customer changed time.
+    $fields['changed'] = BaseFieldDefinition::create('datetime')
+      ->setLabel(t('Changed'))
+      ->setReadOnly(TRUE);
+
+    // Customer mode.
+    $fields['mode'] = BaseFieldDefinition::create('string')
+      ->setLabel(t('Mode'))
+      ->setDescription(t('The mode used to create this customer.'))
+      ->setReadOnly(TRUE);
+
+    return $fields;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function isTranslatable() {
+    return FALSE;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getCreatedTime(): string {
+    return $this->get('created')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getName(): string {
+    return $this->get('name')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getEmail(): string {
+    return $this->get('email')->value;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getMode(): string {
+    return $this->get('mode')->value;
+  }
+
+  /**
+   * @todo: Check if this is the correct way.
+   */
+  public function delete() {
+    /** @var \Drupal\mollie_customers\Entity\CustomerStorage $customerStorage */
+    $customerStorage = \Drupal::service('entity_type.manager')->getStorage('mollie_customer');
+    $customers = $customerStorage->loadMultiple([$this->id()]);
+    return $customerStorage->doDeleteFieldItems($customers);
+  }
+
+}
diff --git a/modules/mollie_customers/src/Entity/CustomerStorage.php b/modules/mollie_customers/src/Entity/CustomerStorage.php
new file mode 100644
index 0000000..18b85b8
--- /dev/null
+++ b/modules/mollie_customers/src/Entity/CustomerStorage.php
@@ -0,0 +1,162 @@
+<?php
+
+namespace Drupal\mollie_customers\Entity;
+
+use Drupal\Component\Serialization\Json;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityStorageException;
+use Drupal\Core\Language\LanguageInterface;
+use Mollie\Api\Exceptions\ApiException;
+use Mollie\Api\Resources\BaseResource;
+use Mollie\Api\Resources\Customer as MollieCustomer;
+use Mollie\Api\Resources\Payment as MolliePayment;
+
+/**
+ * Class CustomerStorage.
+ *
+ * @package Drupal\mollie_customers\Entity
+ */
+class CustomerStorage extends CustomerStorageBase {
+
+  const RESOURCE_NAME = 'customers';
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createEntityFromCustomer(BaseResource $customer): ?EntityInterface {
+    if ($customer instanceof MollieCustomer) {
+      $metadata = Json::decode($customer->metadata);
+
+      $values = [
+        'id' => $customer->id,
+        'created' => $customer->createdAt,
+        'name' => $customer->name,
+        'email' => $customer->email,
+        'mode' => $customer->mode,
+        'changed' => $this->getCustomerChangedDate($customer),
+      ];
+
+      return Customer::create($values);
+    }
+
+    return NULL;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createCustomerFromEntity(EntityInterface $entity): void {
+    if ($entity instanceof Customer) {
+      $metadata = [];
+
+      $values = [
+        'name' => $entity->getName(),
+        'email' => $entity->getEmail(),
+        'locale' => $this->getLocaleByCurrentContentLanguage(),
+        'metadata' => Json::encode($metadata),
+      ];
+
+      try {
+        // Create a customer on the Mollie side.
+        $customer = $this->mollieApiClient->customers->create($values);
+        // Update the entity with the information added by Mollie.
+        // TODO: This might be incomplete. Look for a way to replace $entity.
+        $entity->setOriginalId($customer->id);
+        $entity->set('id', $customer->id);
+      }
+      catch (ApiException $e) {
+        watchdog_exception('mollie', $e);
+        throw new EntityStorageException('An error occurred while creating the customer.');
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function deleteCustomerFromEntity(EntityInterface $entity): void {
+    if ($entity instanceof Customer) {
+
+      try {
+        // Delete a customer on the Mollie side.
+        $customer = $this->mollieApiClient->customers->delete($entity->id());
+      }
+      catch (ApiException $e) {
+        watchdog_exception('mollie', $e);
+        throw new EntityStorageException('An error occurred while deleting the customer.');
+      }
+    }
+  }
+
+  /**
+   * Returns the date the customer last changed in ISO 8601 format.
+   *
+   * @param \Mollie\Api\Resources\Customer $customer
+   *   Payment.
+   *
+   * @return string
+   *   Date the customer last changed in ISO 8601 format.
+   */
+  protected function getCustomerChangedDate(MollieCustomer $customer): string {
+    $changedDate = $customer->createdAt;
+
+    foreach ($this->getCustomerDateFields() as $dateField) {
+      if (property_exists($customer, $dateField)
+        && $customer->{$dateField} > $changedDate) {
+        $changedDate = $customer->{$dateField};
+      }
+    }
+
+    return $changedDate;
+  }
+
+  /**
+   * Returns the date fields known for customers.
+   *
+   * @return array
+   *   Array of date field names.
+   */
+  protected function getCustomerDateFields(): array {
+    return [
+      'createdAt',
+    ];
+  }
+
+  /**
+   * Returns an ISO locale code based on the current content language.
+   *
+   * Best effort to get a locale code to pass to Mollie. Drupal does not have
+   * a country for (anonymous) visitors by default so we cannot construct the
+   * locale from language code and country code. This implementation is based
+   * on the locales currently supported by Mollie.
+   *
+   * @return string
+   */
+  protected function getLocaleByCurrentContentLanguage(): string {
+    $langcode = $this->languageManager
+      ->getCurrentLanguage(LanguageInterface::TYPE_CONTENT)
+      ->getId();
+
+    switch ($langcode) {
+      case 'en':
+        return 'en_US';
+
+      case 'ca':
+        return 'ca_ES';
+
+      case 'nb':
+        return 'nb_NO';
+
+      case 'sv':
+        return 'sv_SE';
+
+      case 'da':
+        return 'da_DK';
+
+      default:
+        $countryCode = strtoupper($langcode);
+        return "{$langcode}_{$countryCode}";
+    }
+  }
+
+}
diff --git a/modules/mollie_customers/src/Entity/CustomerStorageBase.php b/modules/mollie_customers/src/Entity/CustomerStorageBase.php
new file mode 100644
index 0000000..806ae91
--- /dev/null
+++ b/modules/mollie_customers/src/Entity/CustomerStorageBase.php
@@ -0,0 +1,257 @@
+<?php
+
+namespace Drupal\mollie_customers\Entity;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Cache\MemoryCache\MemoryCacheInterface;
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\ContentEntityStorageBase;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Language\LanguageManagerInterface;
+use Drupal\Core\Messenger\MessengerInterface;
+use Drupal\mollie\Mollie;
+use Mollie\Api\Exceptions\ApiException;
+use Mollie\Api\Resources\BaseResource;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Class CustomerStorageBase.
+ *
+ * @package Drupal\mollie_customers\Entity
+ */
+abstract class CustomerStorageBase extends ContentEntityStorageBase {
+
+  const RESOURCE_NAME = '';
+
+  /**
+   * Messenger service.
+   *
+   * @var \Drupal\Core\Messenger\MessengerInterface
+   */
+  protected $messenger;
+
+  /**
+   * Mollie API client.
+   *
+   * @var \Mollie\Api\MollieApiClient|null
+   */
+  protected $mollieApiClient;
+
+  /**
+   * Config factory.
+   *
+   * @var \Drupal\Core\Config\ConfigFactoryInterface
+   */
+  protected $configFactory;
+
+  /**
+   * Language manager.
+   *
+   * @var \Drupal\Core\Language\LanguageManagerInterface
+   */
+  protected $languageManager;
+
+  /**
+   * TransactionStorageBase constructor.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface $entityType
+   *   The entity type definition.
+   * @param \Drupal\Core\Entity\EntityManagerInterface $entityManager
+   *   The entity manager.
+   * @param \Drupal\Core\Cache\CacheBackendInterface $cache
+   *   The cache backend to be used.
+   * @param \Drupal\Core\Messenger\MessengerInterface $messenger
+   *   Messenger service.
+   * @param \Drupal\mollie\Mollie $mollieConnector
+   *   Mollie connector.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $configFactory
+   *   Config factory.
+   * @param \Drupal\Core\Language\LanguageManagerInterface $languageManager
+   *   Language manager.
+   * @param \Drupal\Core\Cache\MemoryCache\MemoryCacheInterface|null $memoryCache
+   *   The memory cache backend.
+   */
+  public function __construct(
+    EntityTypeInterface $entityType,
+    EntityManagerInterface $entityManager,
+    CacheBackendInterface $cache,
+    MessengerInterface $messenger,
+    Mollie $mollieConnector,
+    ConfigFactoryInterface $configFactory,
+    LanguageManagerInterface $languageManager,
+    MemoryCacheInterface $memoryCache = NULL
+  ) {
+    parent::__construct($entityType, $entityManager, $cache, $memoryCache);
+
+    $this->messenger = $messenger;
+    $this->mollieApiClient = $mollieConnector->getClient();
+    $this->configFactory = $configFactory;
+    $this->languageManager = $languageManager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function createInstance(ContainerInterface $container, EntityTypeInterface $entityType) {
+    return new static(
+      $entityType,
+      $container->get('entity.manager'),
+      $container->get('cache.entity'),
+      $container->get('messenger'),
+      $container->get('mollie.mollie'),
+      $container->get('config.factory'),
+      $container->get('language_manager'),
+      $container->get('entity.memory_cache')
+    );
+  }
+
+  /**
+   * Static cache for entities.
+   *
+   * @var \Drupal\Core\Entity\EntityInterface[]
+   */
+  protected $loadedEntities = [];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function doLoadMultiple(array $ids = NULL) {
+    $entities = [];
+
+    foreach ($ids as $id) {
+      // Static caching.
+      if (isset($this->loadedEntities[$id])) {
+        $entities[$id] = $this->loadedEntities[$id];
+        continue;
+      }
+
+      try {
+        if (empty(static::RESOURCE_NAME)) {
+          throw new ApiException('The resource name is invalid.');
+        }
+
+        $customerBase = $this->mollieApiClient->{static::RESOURCE_NAME}->get($id);
+
+        $entity = $this->createEntityFromCustomer($customerBase);
+        if (!is_null($entity)) {
+          $this->loadedEntities[$id] = $entity;
+          $entities[$id] = $this->loadedEntities[$id];
+        }
+      }
+      catch (ApiException $e) {
+        watchdog_exception('mollie', $e);
+      }
+    }
+
+    return $entities;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function has($id, EntityInterface $entity) {
+    // TODO: Implement has() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function purgeFieldItems(ContentEntityInterface $entity, FieldDefinitionInterface $field_definition) {
+    // TODO: Implement purgeFieldItems() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function doDeleteRevisionFieldItems(ContentEntityInterface $revision) {
+    // TODO: Implement doDeleteRevisionFieldItems() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function countFieldData($storage_definition, $as_bool = FALSE) {
+    // TODO: Implement countFieldData() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function readFieldItemsToPurge(FieldDefinitionInterface $field_definition, $batch_size) {
+    // TODO: Implement readFieldItemsToPurge() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function doLoadRevisionFieldItems($revision_id) {
+    // TODO: Implement doLoadRevisionFieldItems() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function doDeleteFieldItems($entities) {
+    foreach ($entities as $entity) {
+      $this->deleteCustomerFromEntity($entity);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function doSaveFieldItems(ContentEntityInterface $entity, array $names = []) {
+    $this->createCustomerFromEntity($entity);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getQueryServiceName() {
+    return 'mollie.mollie';
+  }
+
+  /**
+   * Returns an entity created from the data in a customer base object.
+   *
+   * This method should be implemented by storage classes for specific
+   * customer base types.
+   *
+   * @param \Mollie\Api\Resources\BaseResource $transaction
+   *   Transaction object.
+   *
+   * @return \Drupal\Core\Entity\EntityInterface
+   */
+  abstract protected function createEntityFromCustomer(BaseResource $transaction): ?EntityInterface;
+
+  /**
+   * Creates a customer base object from an entity.
+   *
+   * This method should be implemented by storage classes for specific
+   * customer base types.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   Entity.
+   *
+   * @throws \Drupal\Core\Entity\EntityStorageException
+   */
+  abstract protected function createCustomerFromEntity(EntityInterface $entity): void;
+
+  /**
+   * Deletes a customer base object from an entity.
+   *
+   * This method should be implemented by storage classes for specific
+   * customer base types.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   Entity.
+   *
+   * @throws \Drupal\Core\Entity\EntityStorageException
+   */
+  abstract protected function deleteCustomerFromEntity(EntityInterface $entity): void;
+
+}
diff --git a/modules/mollie_customers/src/Entity/Query/CustomerQuery.php b/modules/mollie_customers/src/Entity/Query/CustomerQuery.php
new file mode 100644
index 0000000..ea7e37c
--- /dev/null
+++ b/modules/mollie_customers/src/Entity/Query/CustomerQuery.php
@@ -0,0 +1,63 @@
+<?php
+
+namespace Drupal\mollie_customers\Entity\Query;
+
+use Mollie\Api\Exceptions\ApiException;
+use Mollie\Api\Resources\CustomerCollection;
+
+/**
+ * Class CustomerQuery.
+ *
+ * @package Drupal\mollie_customers\Entity\Query
+ */
+class CustomerQuery extends CustomerQueryBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function execute() {
+    if ($this->count) {
+      return $this->getCustomersFromMollie()->count();
+    }
+
+    return $this->getCustomerIds();
+  }
+
+  /**
+   * Returns the IDs of the customers for the configured Mollie account.
+   *
+   * @return array
+   *   Array with IDs of the customers for the configured Mollie account.
+   */
+  protected function getCustomerIds(): array {
+    $customerIds = [];
+
+    $customers = $this->getCustomersFromMollie();
+    foreach ($customers as $customer) {
+      /** @var \Mollie\Api\Resources\Customer $customer */
+      $customerIds[$customer->id] = $customer->id;
+    }
+
+    return $customerIds;
+  }
+
+  /**
+   * Returns the customers for the configured Mollie account.
+   *
+   * @return \Mollie\Api\Resources\CustomerCollection
+   *
+   * TODO: Add paging, sorting and parameters.
+   * TODO: Only return customers created by this module.
+   */
+  protected function getCustomersFromMollie(): CustomerCollection {
+    try {
+      return $this->mollieApiClient->customers->page();
+    }
+    catch (ApiException $e) {
+      watchdog_exception('mollie', $e);
+    }
+
+    return new CustomerCollection($this->mollieApiClient, 0, []);
+  }
+
+}
diff --git a/modules/mollie_customers/src/Entity/Query/CustomerQueryBase.php b/modules/mollie_customers/src/Entity/Query/CustomerQueryBase.php
new file mode 100644
index 0000000..ebb2f90
--- /dev/null
+++ b/modules/mollie_customers/src/Entity/Query/CustomerQueryBase.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace Drupal\mollie_customers\Entity\Query;
+
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Entity\Query\QueryBase;
+use Mollie\Api\MollieApiClient;
+
+/**
+ * Class CustomerQueryBase.
+ *
+ * @package Drupal\mollie_customers\Entity\Query
+ */
+abstract class CustomerQueryBase extends QueryBase {
+
+  /**
+   * Mollie API client.
+   *
+   * @var \Mollie\Api\MollieApiClient
+   */
+  protected $mollieApiClient;
+
+  /**
+   * CustomerQueryBase constructor.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface $entityType
+   *   The entity type definition.
+   * @param string $conjunction
+   *   - AND: all of the conditions on the query need to match.
+   *   - OR: at least one of the conditions on the query need to match.
+   * @param array $namespaces
+   *   List of potential namespaces of the classes belonging to this query.
+   * @param \Mollie\Api\MollieApiClient $mollieApiClient
+   *   Mollie API client.
+   */
+  public function __construct(
+    EntityTypeInterface $entityType,
+    string $conjunction,
+    array $namespaces,
+    MollieApiClient $mollieApiClient
+  ) {
+    parent::__construct($entityType, $conjunction, $namespaces);
+
+    $this->mollieApiClient = $mollieApiClient;
+  }
+
+}
diff --git a/modules/mollie_customers/src/Form/CustomerDeleteForm.php b/modules/mollie_customers/src/Form/CustomerDeleteForm.php
new file mode 100644
index 0000000..a5ee2e4
--- /dev/null
+++ b/modules/mollie_customers/src/Form/CustomerDeleteForm.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace Drupal\mollie_customers\Form;
+
+use Drupal\Core\Entity\ContentEntityConfirmFormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\mollie_customers\Entity\CustomerStorage;
+
+/**
+ * Class CustomerDeleteForm.
+ *
+ * @package Drupal\mollie_customers\Form
+ */
+class CustomerDeleteForm extends ContentEntityConfirmFormBase {
+
+  /**
+   * Returns the question to ask the user.
+   *
+   * @return string
+   *   The form question. The page title will be set to this value.
+   */
+  public function getQuestion()
+  {
+    // TODO: Implement getQuestion() method.
+  }
+
+  /**
+   * Returns the route to go to if the user cancels the action.
+   *
+   * @return \Drupal\Core\Url
+   *   A URL object.
+   */
+  public function getCancelUrl()
+  {
+    // TODO: Implement getCancelUrl() method.
+  }
+
+  /**
+   * {@inheritdoc}
+   *
+   * Delete the entity and log the event. logger() replaces the watchdog.
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $entity = $this->getEntity();
+    $entity->delete();
+
+    $this->logger('mollie_customers')->notice('@type: deleted %title.',
+      [
+        '@type' => $this->entity->bundle(),
+        '%title' => $this->entity->label(),
+      ]);
+
+    $form_state->setRedirect('entity.mollie_customer.collection');
+  }
+
+}
diff --git a/modules/mollie_customers/src/Form/CustomerForm.php b/modules/mollie_customers/src/Form/CustomerForm.php
new file mode 100644
index 0000000..c2485a0
--- /dev/null
+++ b/modules/mollie_customers/src/Form/CustomerForm.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace Drupal\mollie_customers\Form;
+
+use Drupal\Component\Datetime\TimeInterface;
+use Drupal\Component\Uuid\UuidInterface;
+use Drupal\Core\Entity\ContentEntityForm;
+use Drupal\Core\Entity\EntityRepositoryInterface;
+use Drupal\Core\Entity\EntityTypeBundleInfoInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\mollie\Mollie;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Class CustomerForm.
+ *
+ * @package Drupal\mollie_customers\Form
+ */
+class CustomerForm extends ContentEntityForm {
+
+  /**
+   * UUID generator.
+   *
+   * @var \Drupal\Component\Uuid\UuidInterface
+   */
+  protected $uuid;
+
+  /**
+   * Mollie API client.
+   *
+   * @var \Drupal\mollie\Mollie
+   */
+  protected $mollieApiClient;
+
+  /**
+   * PaymentForm constructor.
+   *
+   * @param \Drupal\Core\Entity\EntityRepositoryInterface $entityRepository
+   *   The entity repository service.
+   * @param \Drupal\Component\Uuid\UuidInterface $uuid
+   *   UUID generator.
+   * @param \Drupal\mollie\Mollie $mollieApiClient
+   *   Mollie API client.
+   * @param \Drupal\Core\Entity\EntityTypeBundleInfoInterface $entityTypeBundleInfo
+   *   The entity type bundle service.
+   * @param \Drupal\Component\Datetime\TimeInterface $time
+   *   The time service.
+   */
+  public function __construct(
+    EntityRepositoryInterface $entityRepository,
+    UuidInterface $uuid,
+    Mollie $mollieApiClient,
+    EntityTypeBundleInfoInterface $entityTypeBundleInfo = NULL,
+    TimeInterface $time = NULL
+  ) {
+    parent::__construct($entityRepository, $entityTypeBundleInfo, $time);
+
+    $this->uuid = $uuid;
+    $this->mollieApiClient = $mollieApiClient;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity.repository'),
+      $container->get('uuid'),
+      $container->get('mollie.mollie'),
+      $container->get('entity_type.bundle.info'),
+      $container->get('datetime.time')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function form(array $form, FormStateInterface $form_state) {
+    $form = parent::form($form, $form_state);
+    return $form;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $formState) {
+    parent::submitForm($form, $formState);
+  }
+
+}
diff --git a/src/Controller/MollieEntityBaseController.php b/src/Controller/MollieEntityBaseController.php
new file mode 100644
index 0000000..2c20fb8
--- /dev/null
+++ b/src/Controller/MollieEntityBaseController.php
@@ -0,0 +1,35 @@
+<?php
+
+namespace Drupal\mollie\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Entity\EntityInterface;
+use Drupal\mollie_customers\Entity\Customer;
+
+/**
+ * Class MollieEntityBaseController.
+ *
+ * @package Drupal\mollie\Controller
+ */
+class MollieEntityBaseController extends ControllerBase {
+
+  /**
+   * Returns the title for an entity.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   Entity.
+   *
+   * @return string
+   *   Title for the entity.
+   */
+  protected function entityTitle(EntityInterface $entity): string {
+    return $this->t(
+      '@type @label',
+      [
+        '@type' => $entity->getEntityType()->getLabel(),
+        '@label' => $entity->label(),
+      ]
+    );
+  }
+
+}
diff --git a/src/Mollie.php b/src/Mollie.php
index b028868..c0c889f 100644
--- a/src/Mollie.php
+++ b/src/Mollie.php
@@ -8,6 +8,7 @@ use Drupal\Core\Entity\Query\QueryInterface;
 use Drupal\Core\Messenger\MessengerInterface;
 use Drupal\Core\Site\Settings;
 use Drupal\mollie\Entity\Query\PaymentQuery;
+use Drupal\mollie_customers\Entity\Query\CustomerQuery;
 use Mollie\Api\Exceptions\ApiException;
 use Mollie\Api\Exceptions\IncompatiblePlatform;
 use Mollie\Api\MollieApiClient;
@@ -144,6 +145,14 @@ class Mollie {
         $this->getClient()
       );
     }
+    if ($entityType->id() === 'mollie_customer') {
+      return new CustomerQuery(
+        $entityType,
+        $conjunction,
+        ['\Drupal\mollie\Entity\Query'],
+        $this->getClient()
+      );
+    }
 
     return NULL;
   }
diff --git a/src/MollieEntityBasePermissions.php b/src/MollieEntityBasePermissions.php
new file mode 100644
index 0000000..ab38b5c
--- /dev/null
+++ b/src/MollieEntityBasePermissions.php
@@ -0,0 +1,85 @@
+<?php
+
+namespace Drupal\mollie;
+
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Class MollieEntityBasePermissions.
+ *
+ * @package Drupal\mollie
+ */
+class MollieEntityBasePermissions implements ContainerInjectionInterface {
+
+  use StringTranslationTrait;
+
+  /**
+   * Entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * CustomerPermissions constructor.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entityTypeManager
+   *   Entity type manager.
+   */
+  protected function __construct(EntityTypeManagerInterface $entityTypeManager) {
+    $this->entityTypeManager = $entityTypeManager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity_type.manager')
+    );
+  }
+
+  /**
+   * Returns permissions for operations on entities of a given type.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface $entityType
+   *   Entity type.
+   *
+   * @return array
+   *   Array with permissions.
+   */
+  protected function entityBasePermissions(EntityTypeInterface $entityType): array {
+    $permissions = [];
+
+    foreach ($this->getAvailableOperations($entityType) as $operation) {
+      $permissions["$operation {$entityType->id()} entities"] = [
+        'title' => ucfirst(
+          $this->t('@operation @label entities', [
+            '@operation' =>  $operation,
+            '@label' => $entityType->getLabel()
+          ])
+        ),
+      ];
+    }
+
+    return $permissions;
+  }
+
+  /**
+   * Returns available operations on entities of a given type.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeInterface $entityType
+   *   Entity type.
+   *
+   * @return array
+   *   Array with operations.
+   */
+  protected function getAvailableOperations(EntityTypeInterface $entityType): array {
+    return ['create', 'view'];
+  }
+
+}