JSON Server is a tool that generates a fully functional fake REST API from a JSON file in under 30 seconds without requiring any code to be written. The project is maintained by typicode and serves as a rapid prototyping and frontend testing solution for developers who need mock data and API endpoints quickly.
The core functionality revolves around creating a db.json or db.json5 file containing data, then starting the JSON Server process which automatically exposes that data as a REST API accessible at localhost:3000. The tool handles all standard CRUD operations on array resources like posts and comments, as well as singular object resources like profiles. This eliminates the need to set up a backend server during development or testing phases.
JSON Server includes sophisticated querying capabilities built directly into the API. It supports advanced filtering through operators including equality checks, less than and greater than comparisons, inclusion in comma-separated lists, and string operations like contains, startsWith, and endsWith. The API also provides sorting functionality and pagination with configurable page sizes and page numbers. For more complex filtering scenarios, users can pass JSON objects through the _where parameter to override standard query parameters. The embed feature allows related resources to be included in responses, and the tool can automatically delete dependent records when parent records are removed.
The project supports serving static files from a public directory by default, with the ability to configure additional static directories. These files are served with standard MIME types, supporting HTML, CSS, JavaScript, images, and other assets alongside the JSON API responses.
According to GitGenius activity tracking, the repository has a median issue and pull request response latency of 98 hours across 110 tracked items, though the mean latency is significantly higher at 3216.3 hours, indicating some older items with extended response times. The primary maintainer typicode has been involved in 67 tracked events, with contributors MickL and BigSamu also actively involved with 10 and 9 events respectively. The bug label represents the most active issue category tracked by GitGenius.
The repository is currently in a beta v1 phase with documentation noting that breaking changes should be expected, while a stable v0.17.4 version remains available for users preferring stability. Migration from v0 to v1 involves several behavioral changes including ID handling as strings with auto-generation, pagination parameter changes from _limit to _per_page, relationship embedding syntax changes from _expand to _embed, and removal of the --delay CLI option in favor of browser DevTools throttling.
The project has attracted sponsorship from multiple companies including Mockend, Zuplo, Mintlify, Tower, and SerpAPI at the gold level, demonstrating significant adoption and community support. JSON Server is classified across multiple domains including REST API, mock server, fake data generation, JSON database functionality, rapid prototyping, frontend testing, CRUD operations, data simulation, and general development tooling.
