Etherpad

Etherpad is an open-source, web-based real-time collaborative editor that enables multiple users to simultaneously edit the same plain text document, referred to as a pad. Edits appear in real time across all connected clients, with per-user cursors and color-coded contributions.

It was developed by AppJet and released to the public in the late 2000s as open-source. After AppJet’s closure, the community formed the Etherpad Foundation to maintain the core project. The software evolved into Etherpad Lite, a lightweight, self-hostable edition, and spawned numerous forks and hosted services that extend or customize its functionality.

Features commonly associated with Etherpad include real-time multi-user editing, per-user color cursors, and a built-in chat for pad participants. It provides revision history and time-travel to previous document states, and supports export options such as HTML and plain text, with additional formats possible through plugins. The system is designed to be extendable via a plugin architecture, enabling features like code formatting, spell checking, or additional integrations. Access control and embedding capabilities allow Etherpad to be used in various collaborative contexts.

Architecture and operation are based on a client-server model. The server stores pads and revision history and coordinates synchronization among clients using an operational transformation approach to resolve concurrent edits. The client runs in a web browser and communicates with the server over WebSocket or similar protocols. Etherpad is typically run on Node.js and can be self-hosted, often backed by a database for persistence.

Usage and impact: Etherpad has been employed for collaborative writing in education, software development documentation, and lightweight collaborative documentation workflows. It has influenced other real-time editors and remains available in multiple hosted and self-hosted deployments, though some users have migrated to newer stacks or commercial offerings.