EJDB2 vs RocksDB

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.

RocksDB is an embeddable, persistent key-value store for applications that need fast storage. It stores keys and values as arbitrary byte arrays, with ordering determined by a comparator chosen by the user. Its log-structured merge design allows configuration of tradeoffs among write, read, and space amplification, and the project describes it as optimized for low-latency storage on flash drives and high-speed disks. The C++ library supports opening and closing databases, reads and writes, merging, and compaction filters. Described uses include database storage engines, application data caches, and embedded workloads. Multi-threaded compactions support databases holding multiple terabytes; the project describes an audience of application servers storing up to a few terabytes on local or remote systems. RocksDB also has a Java wrapper, RocksJava, with artifacts published through Maven. It is free and open source under either GPLv2 or Apache 2.0, at the user's choice. Building requires GCC 11 or later or Clang 10 or later for C++20 support; values must be smaller than 4 GB.