API007warningFree tier

untyped-api-response

API endpoint has no typed response — consumers can't rely on the response shape.

Applies to: JavaScript, Python, TypeScript

Why this matters

Untyped API responses prevent TypeScript/OpenAPI code generation, break IDE autocompletion for consumers, and let the response shape drift silently. Add response_model (FastAPI), res.json<Type>() (Express), or NextResponse.json<Type>() (Next.js) to every endpoint.

Catch it before it ships

pip install stablestack # or: npx stablestackstablestack # scans your project, API007 includedstablestack explain API007

False positive in your codebase? Suppress a single line with # noqa: API007

More API Contracts checks

unhandled-api-error

API calls without error handling will crash on network failures

inconsistent-api-naming

Mixed naming conventions (snake_case/camelCase) in API code cause bugs

missing-content-type

POST/PUT requests without Content-Type may fail or be misinterpreted

hardcoded-api-url

Hardcoded API URLs make it hard to switch between environments

api-type-alignment

Backend endpoints should have response_model; frontend should use generated types.

cross-file-type-mismatch

Cross-file type mismatch between API endpoint and client call site.