OpenAPI validator
Validate and lint OpenAPI 3.x with source locations.
This check runs on the server. Input and results are not saved as execution history; hosted allowances apply.
About OpenAPI validator
Validate an OpenAPI 3.x document and inspect actionable errors, source lines and operation quality warnings.
When to use it
Check an API contract before importing it into a mock or client generator.
Missing info.version → source path, line and validation reasonHow to use it
- Paste an OpenAPI JSON or YAML document.
- Review structural errors and operation warnings.
- Fix the source at the reported line and validate again.
Fix a contract at its source
Paste JSON or YAML for OpenAPI 3.0, 3.1 or 3.2. Structural validation checks the document and local references, while source locations point back to the original editor lines. Separate warnings identify missing summaries, missing operation IDs and repeated operation IDs that can make generated clients difficult to use.
External references are never fetched from URLs or the filesystem. Bundle a multi file specification before relying on a complete validation result. The tool does not repair missing required fields or upgrade your document. Fix validation errors before importing the contract into OpenAPI to mock, then review warnings for a clearer client and documentation experience.
Limits & privacy
64 KiB source, 64 nesting levels, up to 100 errors and 100 warnings. OpenAPI 3.0, 3.1 and 3.2. External references are reported but never fetched; bundle them first for complete validation. No document repair or code execution. Numbers that would lose precision are rejected. Source is not retained.
Use this tool from the API reference or connect through the SDK, CLI, SSH, or MCP. Hosted calls share your plan allowances.