It allows two-way synchronization between the Realm Object Server[7][8] and the client-side databases that belong to the given logged-in user.
Both a developer and a commercial edition[9] was released, along with a business license[10] for integrating with other database management systems such as PostgreSQL.
While the proprietary sync service wil be discontinued, the database will still be available as open-source, but will no longer be maintained by the MongoDB team.
Realm's development began in the end of 2010 by Alexander Stigsen, along with Bjarne Christiansen,[15] under the name TightDB.
TightDB renamed its product to Realm in September 2014, and released it for public testing.