UnQLite

UnQLite is an in-process software library that implements a self-contained, serverless, zero-configuration, transactional NoSQL database engine. UnQLite is a document store database similar to MongoDB, Redis, CouchDB, etc. as well as a standard Key/Value store similar to BerkeleyDB, LevelDB, etc. UnQLite is an embedded NoSQL (Key/Value store and Document-store) database engine. Unlike most other NoSQL databases, UnQLite does not have a separate server process. UnQLite reads and writes directly to ordinary disk files. A complete database with multiple collections is contained in a single disk file. The database file format is cross-platform, you can freely copy a database between 32-bit and 64-bit systems or between big-endian and little-endian architectures. UnQLite is a Self-Contained C library without dependency. Built with a powerful disk storage engine which support O(1) lookup.