sharedb
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JSON OT database backend
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# ShareDB
[](https://npmjs.org/package/sharedb)
[](https://coveralls.io/github/share/sharedb?branch=master)
ShareDB is a realtime database backend based on [Operational Transformation
(OT)](https://en.wikipedia.org/wiki/Operational_transformation) of JSON
documents. It is the realtime backend for the [DerbyJS web application
framework](http://derbyjs.com/).
For questions, discussion and announcements, join the [ShareJS mailing
list](https://groups.google.com/forum/?fromgroups#!forum/sharejs) or [check the FAQ](./docs/faq.md).
Please report any bugs you find to the [issue
tracker](https://github.com/share/sharedb/issues).
## 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
[<img src="examples/counter/demo.gif" height="300">](examples/counter)
### Leaderboard
[<img src="examples/leaderboard/demo.gif" height="436">](examples/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](https://jekyllrb.com/), and require Ruby >2.4.0 and [Bundler](https://bundler.io/):
```bash
gem install jekyll bundler
```
The docs can be built locally and served with live reload:
```bash
npm run docs:install
npm run docs:start
```