Drupal 8 Cache Backport is a module that brings Drupal 8 cache tags and cache max-age back to Drupal 7 (If there is interest, cache contexts will follow).
It is different from the 'cachetags' module in that it uses a cache decorator approach and works with render arrays and the page cache for any cache bins out of the box. It can also use any other cache backend as backend and does not need specific implementations for e.g. memcache, redis or mongodb.
It is also more heavily influenced by the architecture of Drupal 8.