MongoDB

MongoDB is an open-source document database that stores data as BSON documents grouped into collections. Each document is a self-contained JSON-like object with a flexible schema.

Key features

• Flexible schema. Documents in the same collection can have different shapes; no migrations to add fields.
• Aggregation pipeline. Query and transformation framework supporting grouping, joins ($lookup), and faceted search.
• Horizontal scaling. Built-in sharding distributes data across nodes by shard key.
• Replica sets. Automatic failover and read scaling across replica members.
• Change streams. Reactive event stream of inserts, updates, and deletes.

Origin

Released in 2009 by 10gen (later renamed MongoDB Inc.) and made open source under the AGPL. The Server Side Public License (SSPL) replaced AGPL in 2018.