CKEditor for Rails.
This gem vendors CKEditor 3.6.3 for Rails 3 and greater.
The files will be added to the asset pipeline and available for you
to use.
Include ckeditor-rails in your Gemfile:
gem 'ckeditor-rails'
Now you can include it on the asset pipeline:
//= require ckeditor
You can also use it standalone in your views:
<%= javascript_include_tag 'ckeditor/ckeditor' %>
Important: It's important you define the CKEDITOR_BASEPATH global
variable before you include the ckeditor code. This will make ckeditor
work with theasset pipeline on production, otherwise you'll see a white screen
where CKEditor should be shown. More info here.
<script type="text/javascript">
    var CKEDITOR_BASEPATH = '/ckeditor/';
</script>
<%= javascript_include_tag 'ckeditor/ckeditor' %>