UnQLite!

MariaDB is a backward compatible, drop-in replacement of the MySQL® Database Server. It includes all major open source storage engines.

MongoDB (from "humongous") is a scalable, high-performance, open source NoSQL database. The database is document-oriented so it manages collections of JSON-like documents. Many applications can thus model data in a more natural way, as data can be nested in complex hierarchies and still be query-able and indexable.

Apache CouchDB is a distributed, fault-tolerant and schema-free document-oriented database accessible via a RESTful HTTP / JSON API. It includes incremental map / reduce mechanics for queries and keeps data safe with an append-only datastore.

RethinkDB pushes JSON to your apps in realtime.

Oracle Database delivers industry leading performance, scalability, security and reliability on a choice of clustered or single-servers running Windows, Linux, and UNIX. It provides comprehensive features to easily manage the most demanding transaction processing, business intelligence, and content management applications.

Cockroach is a distributed key/value datastore which supports ACID transactional semantics and versioned values as first-class features. The primary design goal is global consistency and survivability, hence the name. Cockroach aims to tolerate disk, machine, rack, and even datacenter failures with minimal latency disruption and no manual intervention. Cockroach nodes are symmetric; a design goal is one binary with minimal configuration and no required auxiliary services.

Couchbase is the NoSQL database market share leader, with production deployments at AOL, Deutsche Post, NTT Docomo, Salesforce.com, Turner Broadcasting Systems, Zynga and hundreds of other organizations worldwide. Couchbase products enable a more flexible, scalable, high-performance, and cost-effective approach to data management than relational database solutions and are particularly well suited for web applications deployed on virtualized or cloud infrastructures, and mobile applications requiring real-time data synchronization between devices and the cloud. Couchbase is a privately held company funded by Accel Partners, Ignition Partners, Mayfield Fund and North Bridge Venture Partners. www.couchbase.com »

Azure DocumentDB is a NoSQL document database service designed from the ground up to natively support JSON and JavaScript directly inside the database engine. It’s the right solution for web and mobile applications when predictable throughput, low latency, and flexible query are key. Microsoft consumer applications like OneNote already use DocumentDB in production to support millions of users.

HSQLDB (Hyper Structured Query Language Database) is a relational database management system written in Java. It has a JDBC driver and supports a large subset of SQL-92 and SQL:2008 standards. It offers a fast, small (around 1300 kilobytes in version 2.2) database engine which offers both in-memory and disk-based tables. Embedded and server modes are available.

Titan is a scalable graph database optimized for storing and querying graphs containing hundreds of billions of vertices and edges distributed across a multi-machine cluster. Titan is a transactional database that can support thousands of concurrent users executing complex graph traversals in real time.

Amazon DynamoDB is a fully managed NoSQL database service offered by Amazon.com as part of the Amazon Web Services portfolio. It was announced by Amazon CTO Werner Vogels on January 18, 2012.OverviewDynamoDB differs from other Amazon services by allowing developers to purchase a service based on throughput, rather than storage. Although the database does not automatically scale, administrators can request more throughput and DynamoDB will spread the data and traffic over a number of servers using solid-state drives, allowing predictable performance. It offers integration with Hadoop via Elastic MapReduce.DynamoDB is proprietary software, but has been compared to a managed version of the open-source software database Apache Cassandra.Language bindingsLanguages with DynamoDB binding include Java, Node.js, .NET, Perl, PHP, Python, Ruby, and Erlang. »