Mock API Response Generator
Build fake JSON API responses from your own schema, with seeded data, CSV/NDJSON export and full HTTP responses.
Fields
How it works
Describe the shape of the response you need — add fields, pick a type for each one
(ID, name, email, price, date, UUID, boolean, lorem text and more), choose how many
records you want, and the mock API response is generated instantly. Switch the body
shape between a plain array, a { data: [...] } wrapper, a
paginated envelope or a single object, and export it as JSON, NDJSON, CSV or a full
HTTP response with status line and headers — including error responses like 404 and
500 for testing your failure paths.
Every record is produced by a seeded random generator, so the same seed always gives you the same fake data — handy for stable test fixtures and snapshot tests. Change the seed (or hit “New random seed”) for a fresh dataset. Everything runs in your browser with plain JavaScript: no account, no API key, no request ever leaves your device, so it works offline and your schema stays private.
Frequently asked questions
How do I generate mock API responses without a server?
Add the fields you need, pick a type for each one (ID, name, email, price, date, UUID, boolean, lorem text and more), set how many records you want, and the response is generated instantly in your browser. You can copy it, download it as JSON, NDJSON or CSV, or export a complete HTTP response with status line and headers to paste into a mock server, a fixture file or a unit test.
Is this fake JSON data generator free and does my schema get uploaded?
It is completely free, with no account and no API key, and nothing is uploaded. The generator is plain JavaScript running on your device, so your field names, your schema and the generated data never touch a server — unlike hosted fake-data tools that process your schema in the cloud. It even keeps working offline once the page has loaded.
Can I get the same mock data every time I generate it?
Yes. Every dataset is produced by a seeded random generator, so the same seed with the same fields always returns exactly the same records. That makes the output safe to use as a stable test fixture or snapshot. Change the seed, or press New random seed, whenever you want a different dataset.