HTML5-Powered WYSIWYG Editor: Mercury
Mercury is a HTML5-powered WYSIWYG editor similar to the popular ones like TinyMCE or CKEditor but with a different usage experience.
Rather than being positioned inside a given element, it appears over the complete web page and can be used to edit the whole page or any number specified areas.
It supports previewing the edited content and inserting links, images, videos or tables. File uploads can be accomplished with drag 'n' drops.
Snippets can be defined and inserted quickly with the help of a sidebar. And, a similar sidebar exists for taking notes.
Also, collaborative editing is supported. Just edit any page that others are working on at the same time and see their changes in real time.
Mercury can be either installed as a Rails gem or by including the necessary JS and CSS files into our web pages.