The tinymce-rails gem integrates the TinyMCE editor with the Rails asset pipeline.
This gem is compatible with Rails 3.1.1 and higher (including Rails 4).
Support for TinyMCE 4 is currently available in the tinymce-4 branch. For the time being, parallel versions of TinyMCE (3.5.x and 4.x) will be maintained. However TinyMCE 4 will eventually be promoted to the master branch.