RethinkDB is an open-source distributed json database. It scales to multiple machine using very little effort. RethinkDB have very good features including distribute JSON document with query language (play with query language),  help to control/setup the cluster and many more. RethinkDB is very easy to setup and learn.

ReThinkDB URL      http://www.rethinkdb.com
ReThinkDB Installation    http://www.rethinkdb.com/docs/install/
ReThinkDB Quick Start    http://www.rethinkdb.com/docs/quickstart/
ReThinkDB Examples    http://www.rethinkdb.com/docs/examples/
ReThinkDB API (Javascript)    http://www.rethinkdb.com/api/javascript/
ReThinkDB API (Python)    http://www.rethinkdb.com/api/python/
ReThinkDB API (Ruby)    http://www.rethinkdb.com/api/ruby/

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