Etherpad (previously known as EtherPad) is an open-source, web-based collaborative real-time editor, allowing authors to simultaneously edit a text document, and see all of the participants' edits in real-time, with the ability to display each author's text in their own color. There is also a chat box in the sidebar to allow meta communication.
First launched in November 2008, the software was acquired by Google in December 2009, and released as open source later that month. Further development is coordinated by the Etherpad Foundation.
Features and implementation
Anyone can create a new collaborative document, known as a "pad". Each pad has its own URL, and anyone who knows this URL can edit the pad and participate in the associated chats. Password-protected pads are also possible. Each participant is identified by a color and a name.
The software auto-saves the document at regular, short intervals, but participants can permanently save specific versions (checkpoints) at any time. Merging of changes is handled by operational transform. A "time slider" feature...