OpenAPI Validator

oas-validator is a JavaScript library designed for parsing and validating OpenAPI 3.x definitions. The current stable version is 5.0.8. It operates as an assertion-based validator, meaning it ceases validation upon encountering the first structural error, which is crucial for preventing a cascade of spurious errors. However, it also offers a 'lint' option to report multiple warnings for non-critical issues. Key differentiators include its internal use of `reftools` for JSON Pointer and Reference resolution, a transition from older implementations like `jgeXml`. The library supports both Promise-based and callback-based asynchronous usage patterns, catering to different integration preferences. Its primary use case is ensuring the correctness and adherence to the OpenAPI specification of API definitions, often integrated into CI/CD pipelines or development tooling.