missing-content-type
POST/PUT requests without Content-Type may fail or be misinterpreted
Applies to: Go, JavaScript, Python, Ruby, Rust, TypeScript
Why this matters
When you send data to an API without specifying Content-Type, the server might not understand your data format. Always set Content-Type: application/json when sending JSON data.
Catch it before it ships
pip install stablestack # or: npx stablestackstablestack # scans your project, API003 includedstablestack explain API003API003 is part of the Pro rule set. See pricing — the free tier ships 24 checks with no signup.
False positive in your codebase? Suppress a single line with # noqa: API003
More API Contracts checks
unhandled-api-error
API calls without error handling will crash on network failures
API002inconsistent-api-naming
Mixed naming conventions (snake_case/camelCase) in API code cause bugs
API004hardcoded-api-url
Hardcoded API URLs make it hard to switch between environments
API005api-type-alignment
Backend endpoints should have response_model; frontend should use generated types.
API006cross-file-type-mismatch
Cross-file type mismatch between API endpoint and client call site.
API007untyped-api-response
API endpoint has no typed response — consumers can't rely on the response shape.