EJDB2 vs eXtremeDB

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.

eXtremeDB is an in-memory database system designed for embedded devices and applications. It can combine in-memory and persistent storage within one database system. Interfaces include native APIs, REST, SQL, ODBC, and JDBC, with language APIs for C/C++, Java, Python, C#, Go, and Rust. For time-series data, a sequence type provides columnar storage. Distributed options include High Availability, Cluster, and Active Replication Fabric for replication across IoT tiers. Network communications can use TLS/SSL with OpenSSL or wolfSSL. Technical specifications list maximum database sizes of 4 GB on 32-bit architectures and 18.4 exabytes on 64-bit architectures. eXtremeDB supports Android, iOS, Linux, macOS, and Windows, and can be self-hosted. Evaluation downloads are listed for Linux, macOS, and Windows; custom trial packages can be requested for other platforms. McObject offers annual engineering support contracts that include software updates and a 50 percent discount on major upgrades. Commercial licensing is paid, with pricing available on request, and a 60-day trial is listed.