API Response Generator

An API mockup tool creates realistic mock API responses without a real backend. Pick a resource such as users or orders, choose the fields, how many records and the HTTP status, and it builds the JSON body, the response headers and the code to call the endpoint. Use it for frontend work, tests, demos and API documentation.

Yes, it is completely free, with no sign-up and no limits. Everything runs in your browser: your fields, settings and history stay on your device and nothing is sent to a server.

Copy or download the response body as JSON, the headers as text, a cURL command, a fetch() snippet, a JavaScript mock module with a mockFetch() helper that waits for your chosen latency, and TypeScript with interfaces generated from your fields.

Choose a resource, switch fields on or off or add your own (name, email, UUID, number range, enum, date, image URL and more), set how many records you need and press Generate response. Lock the seed under More options to get the same JSON every time, which keeps test snapshots stable.

Pick an error status and the body changes to match: 400, 401, 403, 404, 409, 422, 429, 500 and 503 each return an error object with a code, a readable message and a request ID, and 422 lists the invalid fields. Switch the error format to Problem JSON for the RFC 9457 shape with type, title, status, detail and instance.

A paginated response returns one page of records plus what you need to fetch the rest. Here that is a data array, a meta object with the page, page size, total and total pages, links to the first, next and last pages, and matching Link and X-Total-Count headers.