The libraries
ContentTools is one of a collection of libraries, each designed to provide a distinct set of functionality that can either be used standalone or in combination with each other. For example the HTMLString library is used on kicca.com to abbreviate HTML post content in real-time for different viewport dimensions, whereas all the libraries are used for the default editor which comes with ContentTools.
Whilst ContentTools provides a ready-to-go and customizable editor that will prove sufficient for many, the code is intended to be applicable to a wide array of content editing problems. I recommend spending a little time getting to know the other libraries.
All the projects use CoffeeScript and SASS to generate the final JavaScript and CSS, and Grunt is used as the build manager. Clearly this doesn't prevent you from using the code with JavaScript or CSS but I would recommend you take a look at CoffeeScript, SASS and Grunt.
FSM
A minimal finite state machine (FSM) for Javascript.
HTMLString
An HTML parser written in JavaScript that's probably not what you're looking for.
ContentSelect
A JavaScript library providing cross-browser support for content selection.
ContentEdit
A JavaScript library that provides a set of classes for building content-editable HTML elements.
ContentTools
A JavaScript library aimed at building WYSIWYG editors for HTML content.