Everyone else diffs your spec.
We diff your router.
Every serious tool in this category takes a hand-maintained OpenAPI file as its input — the one artifact nobody can keep accurate. These pages say where that matters, and where it doesn’t.
Postman diffs your spec. APIOS diffs your router.
Free is one seat since March 2026. Spec Hub added governance. Here is what that does and doesn't cover.
Read the comparison vs ApidogApidog makes the design the source of truth. We think the code is.
Design-first, done well. The disagreement is about which artifact should be the source of truth.
Read the comparison vs OpticOptic is gone. Here is what to do about it.
Archived January 2026 with no migration path. If you are looking for where to go, start here.
Read the comparisonWhat is the same on every one of these pages
Three claims. If the first one is wrong, nothing else here matters.
- 1
Everyone else starts from a copy
Postman, Apidog, oasdiff, SpecShield, Redocly, Stainless — every one of them takes a hand-maintained specification as its input. That is the artifact that drifts. We read the router that will answer a request this afternoon.
- 2
Nothing publishes itself
The extractor is lexical and it can be wrong, so it never writes to your published API. It opens a proposal, a person reads what the change does to callers, and a different permission publishes it. Automation earns trust by being reviewable.
- 3
What is metered is scale, never safety
Review, breaking-change detection and the audit log are on every tier including free. Putting a smoke detector behind a subscription is not a business model we want.
Measure your own drift first
Connect a repository and we’ll count the endpoints that aren’t in your published reference. It takes about ten minutes and the number is almost never zero.