Show HN: SpecGate – Validate API responses against OpenAPI in real-time

Hey HN,

Over the years, I've built quite a few OpenAPI specs that'd get neglected over time and where the endpoints would eventually drift away from the spec.

I wanted to build something super lightweight that I could drop in during development to double check that my endpoints still match the spec as expected.

SpecGate is a lightweight proxy that checks API responses against the given OpenAPI spec. It'll tell you if there's an undocumented endpoint or if the response doesn't match the spec. I managed to catch about 10 issues with one of my more recent specs as soon as I started using it.

It's possible to run this in production as well, but it currently only logs to stdout/stderr, so keep that in mind if you decide to run it in production.

Would love to hear your feedback on this tool.