Cost / License
- Free
- Open Source
Platforms
- Mac
- Windows
- Linux
- BSD

MariaDB is described as 'Backward compatible, drop-in replacement of the MySQL® Database Server. It includes all major open source storage engines' and is a very popular relational database in the development category. There are more than 50 alternatives to MariaDB for a variety of platforms, including Windows, Linux, Mac, Self-Hosted and Web-based apps. The best MariaDB alternative is SQLite, which is both free and Open Source. Other great apps like MariaDB are PostgreSQL, MySQL Community Edition, MongoDB and Microsoft SQL Server.

NuoDB is a distributed database that can be deployed in any datacenter, in any cloud, anywhere, without the compromises inherent in other New SQL solutions.
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.

H2 is a relational database management system written in Java. It can be embedded in Java applications or run in the client-server mode. The disk footprint (size of the jar file) is about 1 MB.
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...

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...
Mimer SQL is an SQL-based relational database management system from the Swedish company Mimer Information Technology AB (formerly: Upright Database Technology AB), which has been developed and produced since the 1970s.
HBase is an open source, non-relational, distributed database modeled after Google's BigTable and is written in Java. It is developed as part of Apache Software Foundation's Apache Hadoop project and runs on top of HDFS (Hadoop Distributed Filesystem), providing...
An embedded database built on object storage. Unlike traditional LSM-tree storage engines, SlateDB writes data to object storage to provide bottomless storage capacity, high durability, and easy replication.



UnQLite is a in-process software library which implements a self-contained, serverless, zero-configuration, transactional NoSQL database engine. UnQLite is a document store database similar to MongoDB, Redis, CouchDB etc.
CouchDB is not a relational SQL database. It is not an alternative to relational databases.