Generate API contract tests from examples
Turn API examples and schemas into starter contract test assertions so teams can catch response-shape regressions earlier.
Open the tool, then paste the sample input below. Everything runs locally in your browser.
The problem
Manual API tests often check only status codes. Contract tests should also verify required fields, types, headers, and response shape so client integrations fail fast when an API changes unexpectedly.
Sample input
GET /users/123
200 OK
{ "id": "123", "email": "user@example.com", "active": true }Expected output
Assert status is 200
Assert body.id is string
Assert body.email is string
Assert body.active is booleanHow to do it
- Paste an API response example or schema.
- Choose the target test style if available.
- Generate the starter assertions.
- Review field and type checks.
- Copy the result into your test suite.
Common mistakes
- Testing only HTTP status codes.
- Overfitting tests to volatile values such as timestamps.
- Forgetting negative cases and error responses.
- Checking examples that do not match the published schema.
Related tools
FAQ
What should an API contract test assert?
At minimum, check status, required fields, field types, important headers, and known error shapes.
Should I assert every response value?
Usually no. Assert stable contract fields and avoid brittle checks for timestamps, generated IDs, or ordering unless they matter.
Is the API example uploaded?
No. Test generation runs locally in your browser.
Is my data uploaded anywhere?
No. This workflow runs locally in your browser unless you explicitly copy or share the result yourself.
This guide uses browser-local tooling. Avoid pasting production secrets unless you understand what the tool displays and shares.
Continue with adjacent browser-based tools for the same workflow.