CoEditor
Edit documents with others at the same time. Right from the browser.
Features
Real-Time
The fastest real-time collaborative editor on the web, which means you don't notice any annoying lag

History Slider
Slide back time and revert the document to any point in history

Reliable
No disconnects regardless of the number of users
Usage
E-Learning
Collaboration between students and teachers is instant and simple. Research topics together

Cooperative Coding
Develop and brainstorm code samples and algorithms with colleagues

Meeting Notes
Quickly organize information in a meeting environment
Technology
Client-side
Less than 2000 lines of Dojo-powered javascript

Server-side
A python web server capable of Operational Transformation, powered by the Open Cooperative Web Framework

Get it
Completely open source. Grab from github here
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