EJDB2

EJDB2 is a free, MIT-licensed document database delivered as an embeddable C library, with an optional standalone server for network clients. It is best suited to developers shipping self-contained applications that need JSON storage and richer-than-basic document queries. The central choice is whether its compact deployment and JQL outweigh the narrower set of maintained language bindings.

Overview

EJDB2 stores a document database in a single file, using the IOWOW persistent key/value engine underneath. That architecture keeps storage close to the application and avoids a separate database service, which is practical for embedded products and self-hosted deployments. It also means you own deployment, upgrades, and operational decisions rather than receiving a managed service.

The C11 API makes native integration the primary path. EJDB2 is published under the MIT License, so it can be used in proprietary as well as open-source software without a paid edition.

Key features

JQL is an XPath-like query language for JSON documents. It handles filtering and data modification, then adds collection joins, projections, sorting, indexes, and skip, limit, and count options. That is a broad set for document-oriented application work: joins help when related data is split across collections, while projections and pagination controls can keep returned results focused. Teams whose tooling and skills are built around SQL will need to adapt to a different query interface.

The standalone jbs server exposes both HTTP REST and WebSocket endpoints, allowing clients to use EJDB2 over a network instead of only through an in-process library. TLS 1.2 protects those connections, and the server can require a token sent in the X-Access-Token HTTP header. A write-ahead-log option is available when durability matters, and online backup support helps with operational protection of data.

Bindings are associated with C, Dart, Flutter, Java, Node.js, React Native, and Swift, but the project’s post-2025 cleanup leaves only the Java and Node.js bindings maintained. That distinction matters: a tagged binding may exist for another ecosystem without receiving ongoing maintenance. The disabled issues tracker and contribution model based on pull requests also make community support less structured than a product with an active issue queue.

Pricing

There is one free, open-source plan, with no paid tier or trial period. It suits individual developers, commercial teams, and projects that can operate the library themselves and do not need hosted-service features or a vendor subscription.

Platforms

EJDB2 supports macOS, iOS, Linux, and Windows, and is offered through API and self-hosted deployments. The platform range covers desktop, server, and Apple mobile targets, while the maintained Java and Node.js bindings are the safest choices for teams seeking an actively supported language integration.

Who it's for

Choose EJDB2 for an application that benefits from a single-file JSON store, native C11 integration, and optional REST or WebSocket access without introducing a separate database server. Its joins, indexes, projections, and query controls suit document applications that have outgrown simple key-value access.

It is a weaker fit for organizations that require a managed database, broad actively maintained SDK coverage, or a conventional issue-tracking support channel. SQL-first teams should also account for the learning and migration cost of JQL.

Pros and cons

Pros

• Embeddable single-file design: packages storage with the application and supports self-hosted delivery without a separate service.
• Capable document queries: JQL combines filtering, updates, joins, projections, sorting, indexes, and pagination or counting options.
• Optional network layer: REST and WebSocket endpoints, TLS 1.2, token authentication, write-ahead logging, and online backups extend the engine beyond in-process use.
• Permissive cost and licensing: the MIT license and free plan allow use without subscription fees.

Cons

• Limited maintained bindings: only Java and Node.js bindings remain maintained after the 2025 cleanup, raising upkeep concerns for other language ecosystems.
• Less conventional support: the issues tracker is disabled, so teams cannot rely on a normal public issue queue for support or bug coordination.
• Self-managed operations: the embedded approach does not provide a managed service; deployment, durability configuration, and backups remain your responsibility.
• Non-SQL query model: JQL may be a poor match for teams standardized on SQL tooling and practices.

Alternatives

Browse Embedded Databases for a wider field of embeddable options.

Pick Chroma instead if you want a freemium database available across web and mobile platforms, with an Apache 2.0 open-source codebase that also powers Chroma Cloud.

Choose LadybugDB for a free MIT-licensed option offering source code and pre-compiled binaries across a similarly broad platform set.

RxDB is the better alternative when a freemium JavaScript-oriented database with replication, realtime sync, default storages, and a capped free plan fits your application.

Choose SQLite when you want a free embedded SQL engine with no license required.

bbolt is a free open-source Go library and command-line utility for projects that prefer that ecosystem.

Consider ObjectBox if you need a freemium database with a free core and a separate sync offering, plus a free trial.

PouchDB is a free, open-source alternative spanning web and mobile platforms.

Choose Qdrant when a freemium vector-database service with a free cloud tier is the relevant model.

Verdict

EJDB2 is a strong choice for developers who want an MIT-licensed, single-file JSON engine embedded in a native application, with serious JQL queries and an optional secured network server. Look elsewhere if you need a managed offering, broad maintained bindings beyond Java and Node.js, or a conventional issue tracker and support workflow.