MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need.
MongoDB stores data in flexible, JSON-like documents, meaning fields can vary from document to document and data structure can be changed over time.
The document model maps to the objects in your application code, making data easy to work with
Ad hoc queries, indexing, and real time aggregation provide powerful ways to access and analyze your data.
MongoDB is a distributed database at its core, so high availability, horizontal scaling, and geographic distribution are built in and easy to use
MongoDB is free and open-source, published under the GNU Affero General Public License.