share/sharedb

Realtime database backend based on Operational Transformation (OT)

JavaScript

6,540

1,526 commits

updated Oct 9, 2026

See the code

README

ShareDB

NPM Version Test Coverage Status

ShareDB is a realtime database backend based on Operational Transformation (OT) of JSON documents. It is the realtime backend for the DerbyJS web application framework.

For help, questions, discussion and announcements, join the ShareJS mailing list or read the documentation.

Please report any bugs you find to the issue tracker.

Features

  • 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

Documentation

https://share.github.io/sharedb/

Examples

Counter

Leaderboard

Development

Documentation

The documentation is stored as Markdown files, but sometimes it can be useful to run these locally. The docs are served using Jekyll, and require Ruby >2.4.0 and Bundler:

gem install jekyll bundler

The docs can be built locally and served with live reload:

npm run docs:install
npm run docs:start

share/sharedb

Realtime database backend based on Operational Transformation (OT)

JavaScript

6,540

1,526 commits

updated Oct 9, 2026

See the code

README

ShareDB

NPM Version Test Coverage Status

ShareDB is a realtime database backend based on Operational Transformation (OT) of JSON documents. It is the realtime backend for the DerbyJS web application framework.

For help, questions, discussion and announcements, join the ShareJS mailing list or read the documentation.

Please report any bugs you find to the issue tracker.

Features

  • 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

Documentation

https://share.github.io/sharedb/

Examples

Counter

Leaderboard

Development

Documentation

The documentation is stored as Markdown files, but sometimes it can be useful to run these locally. The docs are served using Jekyll, and require Ruby >2.4.0 and Bundler:

gem install jekyll bundler

The docs can be built locally and served with live reload:

npm run docs:install
npm run docs:start

Project health

Overall

3.9/10

Maintained

10/10

Code review

1/10
OpenSSF Scorecard

Latest release

6.0.5 · Oct 6, 2026

Releases this year

6

Significant stargazers

(top 24 of 57)

Josh Abernathy

2,537 followers · starred Mar 2022

Jake Zimmerman

537 followers · starred Feb 2018

Innei

3,489 followers · starred Jul 2024

Ted Mielczarek

197 followers · starred Oct 2017