A json-server alternative with behaviour, not just CRUD

json-server is an npm package that turns a db.json file into a full REST API with one command: every top-level key becomes a collection with GET, POST, PUT, PATCH and DELETE, writes are saved back to the file, and filtering, sorting and pagination come from query parameters. For a front-end that needs a working backend on day one, very little is faster.

At a glance

Where it stops

It is a CRUD mirror of your file. It has no authentication, no roles, no validation beyond what the file shape implies, no concurrency control, no rate limits and no business rules, so it answers almost everything with 200 or 201. That makes it a stand-in for a database, not for an API somebody else designed — your client never meets a 409, a 412, a 422 or a 429 unless you write middleware to produce one.

What is different here

Here the rules come built in and were written by somebody other than you: tickets sell out with a 409, stale versions are refused with 412, validation fails with 422, rate limits answer 429 with Retry-After, tokens expire. Nothing has to be installed or run, the same behaviour is available in the browser and over HTTPS, and each API ships an OpenAPI 3.1 document and a Postman collection.

What json-server does better

• Your own data model, defined in a file you control and can commit next to the front-end.
• Runs locally, so it works in CI with no external dependency at all.
• Writes go straight to db.json, so the state after a test run is easy to inspect.
• Customisable with Express middleware when you need one specific behaviour.

What this playground does better

• Auth, roles, validation, concurrency and rate limits exist without writing middleware.
• Failures happen for domain reasons, so a test exercises how the client copes rather than what you scripted.
• Nothing to install or keep running, and the engine also runs offline in the browser.
• Interactive docs, OpenAPI 3.1 and Postman exports for every API.

Which to use

Use json-server when you need your own data model behind a working REST API in minutes. Use this when the point is to see how a client copes with an API that has rules of its own.

Checked against json-server as of 2026-09.

Other comparisons

• JSONPlaceholder — JSONPlaceholder fakes its writes. If you need a POST that a later GET can find, that is the difference.
• httpbin — httpbin shows you the request. This shows you an API. They answer different questions.
• reqres.in — reqres is a clean, tiny user API with fake auth. The gap is everything past the happy path.
• WireMock — WireMock reproduces the API you already know, exactly. This one gives you an API you do not control.
• Mockoon — Mockoon is for designing your own mock API. This one is an API already designed, with rules you have to discover.
• Beeceptor — Beeceptor gives you a hosted endpoint to inspect and mock. This gives you finished APIs that behave like real ones.
• DummyJSON — DummyJSON has rich sample data and a JWT login. Its writes are simulated; here they persist.
• Postman mock servers — A Postman mock server replays the examples saved in a collection. This one runs an API with state and rules.
• PokeAPI — PokeAPI is the real Pokémon database, read-only. This Pokémon API is invented data you can write to and break.
• SWAPI — SWAPI serves Star Wars data, read-only. This Star Wars API is invented practice data you can change.
• the free mock API landscape — Six free options, what each is genuinely for, and how to tell which one your problem needs.

All 39 mock REST APIs · Getting started guide · About this playground

Last updated 15 October 2026