How it worksPaste an OpenAPI 3 or Swagger 2 spec (JSON; simple YAML works too), pick an endpoint and status code, and get mock data generated from the response schema — $ref resolved, x-faker supported.

OpenAPI / Swagger specOpenAPI / Swagger

Load an OpenAPI spec to start

Mock response

Load a spec, then pick an endpoint to mock

Frontend first, backend later

OpenAPI to Mock Response

Pick an endpoint · $ref resolution · x-faker support · runs locally

🔒Data is processed locally in your browser — never uploaded or stored

No upload, no storage

JSON is processed in memory and never sent to a server.

Share via URL fragment

Share links encode data in the # anchor — never sent to a server.

Remember last edit

Optionally keep your last input locally; clear it with one click.

Why mock from an OpenAPI spec

Paste, pick, done

OpenAPI 3 and Swagger 2 both work: choose the endpoint and status code from dropdowns and the response schema becomes usable mock JSON.

Automatic $ref resolution

Reusable models under components/schemas are expanded automatically — nested references and arrays of objects generate completely.

Realistic fields

Add x-faker keywords (e.g. internet.email) to get real-looking names and emails instead of random strings.

Parallel development

Contract agreed but the API not built yet? Run the frontend on mock responses and swap in the real API later.

Local & private

API specs often describe internal endpoints — everything is parsed and generated on your machine, nothing uploaded.