A mock API generator for the backend that does not exist yet

The problem with mocking inside the app

Most frontend teams reach for one of three things while the API is still being written. They hardcode a fixture into the component, they stand up a small Express or json-server process, or they intercept requests in the client with a library. Each one works, and each one has the same problem: the mock lives inside the codebase, so it has to be written, reviewed, merged, and eventually removed.

That cost is paid again every time the shape of the response changes. It is also paid by the next person, who finds a fixture file and cannot tell whether it still matches production. Mocks that live in the repository tend to rot quietly, and the rot only shows up when someone trusts them.

A generated API moves the mock out of the codebase. The app only ever knows a base URL. The response, the status code, and the delay are edited in a form and take effect on the next request, with no rebuild and no redeploy on either side.

A realistic set of endpoints

A screen usually needs more than one happy path. Grouping the endpoints for one feature means you can build the empty state, the error state, and the slow state without touching the component under test.

GET  /api/orders          200   list of 20 orders
GET  /api/orders/1        200   one order
POST /api/orders          201   the created order
GET  /api/orders/9999     404   { "message": "Not found" }
GET  /api/orders/slow     200   same list, 3000 ms delay

On a free account you can keep 5 projects, each holding 10 endpoint groups of up to 10 endpoints, which is room for several features at once without any of them colliding. Every one of those responses is a body you write yourself, covered in more detail on the fake JSON API page.

An online mock server with nothing to install

The generator runs in the browser, so there is no CLI to install, no SDK to add to your package.json, and no process sitting on a port while you work. You fill in a form and the endpoint answers over HTTPS before you have switched back to your editor.

That is also what makes it shareable. An online mock server has one address, so the same URL works for the person building the screen, the designer checking a state, and the CI job running the suite. Nobody clones anything, and nobody has to be told which port you used.

What it deliberately does not do is keep state. A POST does not change what a later GET returns, because the point is a predictable response, not a second database. The FAQ goes through the rest of the limits.

How the generator works

Compared with running your own mock server

The same job, minus the parts that outlive the sprint.