DuckDB UI vs EJDB2

DuckDB UI is a free browser interface for a local DuckDB instance, added through the ui extension. Start it with `duckdb -ui` or `CALL start_ui()`; it opens in the default browser and is served by an HTTP server embedded in DuckDB, available by default at `http://localhost:4213`. The interface includes a SQL notebook with autocomplete and keyboard shortcuts, a catalog browser, a table explorer with column statistics, and a results viewer with sorting and filtering. The native DuckDB process gives it access to local cores, memory, and files. Queries run locally by default, and queries and data stay on the computer. Connecting to MotherDuck is optional and requires signing in. The UI is built and maintained by MotherDuck. The local server retrieves interface files from ui.duckdb.org, so alternate configured URLs should be trusted because the application can access loaded DuckDB data. The UI cannot be run directly against a read-only database and does not currently support windows_arm64.

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.