ShareDB is a full-stack library for realtime JSON document collaboration. It provides a Node.js server for coordinating and committing edits from multiple clients. It also provides a JavaScript client for manipulating documents, which can be run either in Node.js or in the browser.

The underlying conflict management is handled through Operational Transformation (OT). The implementation of this strategy is delegated to ShareDB’s type plugins.


  • Realtime synchronization of any JSON document
  • Concurrent multi-user collaboration
  • Synchronous editing API with asynchronous eventual consistency
  • Realtime query subscriptions
  • Simple integration with any database
  • Horizontally scalable with pub/sub integration
  • Projections to select desired fields from documents and operations
  • Middleware for implementing access control and custom extensions
  • Ideal for use in browsers or on the server
  • Offline change syncing upon reconnection
  • In-memory implementations of database and pub/sub for unit testing
  • Access to historic document versions
  • Realtime user presence syncing