EJDB2 vs H2 Database Engine

EJDB2 is a free, MIT-licensed JSON database engine implemented as a C library for embedding in applications. It stores data in a single file, using the IOWOW persistent key/value storage engine. Its JQL query language supports filtering, data modification, collection joins, projections, sorting, indexes, and options to skip, limit, or count results; online backup is also listed. For network access, the standalone jbs server provides HTTP REST and WebSocket endpoints. The server supports TLS 1.2, can require an access token in the X-Access-Token HTTP header, and offers a write-ahead-log option for durability. EJDB2 provides a C11 API and lists macOS, iOS, Linux, Windows, and self-hosted availability. The repository links to language bindings and tags the project with C, Dart, Flutter, Java, Node.js, React Native, and Swift, but its changelog says only Java and Node.js bindings are maintained after a 2025 cleanup. The project README says its issues tracker is disabled and welcomes contributions and pull requests. The listed plan is EJDB2 at free.

H2 Database Engine is a free SQL database written in Java. It runs in embedded, server or mixed modes, with databases held on disk or in memory. H2 supports standard SQL and JDBC; server mode also accepts JDBC or ODBC over TCP/IP. A browser-based Console provides autocomplete. Listed database capabilities include transactions, multi-version concurrency and row-level locking, with JSON data support and high availability listed. Compatibility modes cover IBM DB2, Apache Derby, HSQLDB, MS SQL Server, MySQL, Oracle and PostgreSQL. Database files can use AES-128 encryption, while remote JDBC connections can use TLS. H2 is available for Linux, macOS and Windows, as an API, and for self-hosted or web deployment. It is dual licensed under MPL 2.0 or EPL 1.0, allowing integration into and distribution with commercial applications. The JAR is described as around 2.5 MB. The plan costs nothing.