Free mock APIs compared: which one for which job

The free tools in this space fall into three groups, and most of the frustration people have with them comes from reaching into the wrong group. Knowing which is which takes about a minute and saves an afternoon.

At a glance

the free mock API landscape compared with this playground, checked 2026-09.
	Fixed dataset	Reflector	Configurable mock	This playground
	JSONPlaceholder, reqres	httpbin, Postman Echo	Mockoon, WireMock, Beeceptor	funapi.dev
Setup required	None	None	You define every response	None
Writes persist	No	N/A — no resources	If you configure it	Yes
Who wrote the rules	The maintainers	Nobody — it reflects	You did	Somebody else, which is the point
Stateful failures	No	No	Only ones you scripted	Yes — 409, 412, 429 with a cause
Runs offline	No	If self-hosted	Yes	Yes — the engine is in the browser
Spec export	No	No	Usually spec-driven already	OpenAPI 3.1 and Postman
Best for	A body to render	What did my client send	Reproducing one exact contract	Rehearsing how an API misbehaves

Where it stops

The groups are: fixed public datasets you cannot change (JSONPlaceholder, reqres); protocol reflectors with no domain (httpbin, Postman Echo); and configure-your-own mock servers where you define the responses yourself (Mockoon, WireMock, Beeceptor, Prism, Mocky). Each is good at its own job and poor at the others, and none of the first two lets you provoke a stateful failure.

What is different here

This playground is a fourth thing: a simulated API with persistent per-caller state and behaviour that pushes back. You do not configure the responses — the point is that you did not write them, so you find out how your client copes with rules somebody else chose. That is closer to integrating with a real third-party API than any config file can be, and it is the gap the other three groups leave.

What the free mock API landscape does better

A fixed public dataset is better when you want a body to render and nothing more.
A protocol reflector is better when the question is "what did my client actually send".
A configurable mock server is better when you must reproduce one specific third-party contract exactly, or run entirely offline inside CI with no external dependency at all.
A self-hosted option is better where the network will not allow outbound calls.

What this playground does better

Nothing to configure, install or sign up for.
Stateful behaviour with real constraints, so failures happen for reasons.
Every HTTP status code in the catalog reachable from a documented endpoint.
The full engine runs in the browser, so it also works with no network at all.
OpenAPI 3.1 and Postman exports, so anything you practise here moves into your own tooling.

Which to use

Pick by the question you are asking. Rendering a list: a fixed dataset. Debugging your client: a reflector. Reproducing one exact contract: a configurable mock. Learning or rehearsing how an API behaves when things go wrong: this.

Checked against the free mock API landscape 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.
json-server — json-server turns a JSON file into a REST API in seconds. It does not push back — and that is the difference.
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.

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Last updated 2 October 2026