# OpenAPI Support

Spectral has a built-in [OpenAPI Specification](https://openapis.org/specification) ruleset that you can use to validate your OpenAPI files.

Add `extends: "spectral:oas"` ("oas" being shorthand for OpenAPI Specification) to your ruleset file to apply rules for OpenAPI v2 and v3.x, depending on the appropriate OpenAPI version being used (this is automatically detected through [formats](../getting-started/3-rulesets.md#formats)).

You can see a full list of the rules in this ruleset in [OpenAPI Rules](../reference/openapi-rules.md).