SQLite

SQLite is an open source database engine that is used by applications because of its compact size, cross platform stability and serverless functionality. Transactions are consistent, isolated, atomic and durable (ACID) even after system crashes and power failures. No setup or administration is required. Advanced capabilities like partial indexes, indexes on expressions, JSON, common table expressions, and window functions can be offered.
It can be used as an application file format as a complete database is stored in a single cross-platform disk file. It supports databases of terabyte sized and strings of gigabyte sized. It has simple, easy to use API. It is is easy to add into a larger project as it is available as a single ANSI-C source-code file that is easy to compile. Sources are in the public domain that can be used for any purpose. SQLite can be used for the database engine in cellphones,, MP3 players, PDAs, set-top boxes, and other electronic gadgets.