OpenAPI breaking-change detection for API teams.

oasdiff is the open-source toolchain teams use to catch breaking changes in OpenAPI specs before they ship. Run it as a CLI, in CI via the GitHub Action, or open a free side-by-side review of any two specs and share it with your team. oasdiff Pro adds approve / reject on the pull request with a commit-status check that blocks the merge until every breaking change is signed off.

• Diff and changelog. A precise, machine-readable diff between any two OpenAPI specs, plus a human-readable changelog.
• Breaking-change checks. A library of rules that flag changes likely to break API consumers.
• PR annotations. The oasdiff GitHub Action marks breaking changes inline on the changed lines, in the Files Changed tab.
• Free side-by-side review. Turn any comparison into a shareable visual review: add --open to oasdiff breaking or changelog, click the link the GitHub Action adds to each pull request, or paste two specs at oasdiff.com/diff. The specs are encrypted before upload, so the review stays private to whoever holds the link.
• Validate. Catch OpenAPI and JSON Schema violations standalone, no diff required.
• A public model of API changes. OpenAPI gave API definitions a formal model; the OpenAPI Changes Model does the same for API changes: every possible edit to a contract, classified as breaking or not, in one machine-readable file. oasdiff is its reference implementation.

Try it without installing:

docker run --rm -t tufin/oasdiff diff \
  https://raw.githubusercontent.com/oasdiff/oasdiff/main/data/openapi-test1.yaml \
  https://raw.githubusercontent.com/oasdiff/oasdiff/main/data/openapi-test5.yaml

Install:

brew install oasdiff                                                                # macOS
go install github.com/oasdiff/oasdiff@latest                                        # Go
curl -fsSL https://raw.githubusercontent.com/oasdiff/oasdiff/main/install.sh | sh   # macOS or Linux

Or paste two specs at oasdiff.com/diff. Add --open to oasdiff breaking or changelog to open a shareable side-by-side review of the changes in your browser.

For teams that need block-on-merge controls, approve / reject directly on the GitHub PR comment, and per-org policy: see oasdiff Pro.

• Apache-2.0 licensed
• Active development with regular tagged releases
• Used in CI by API teams across SaaS, fintech, dev-tools, and OSS

• Documentation: oasdiff.com/docs
• Support and partnerships: info@oasdiff.com
• Issues and feature requests: github.com/oasdiff/oasdiff/issues
• Terms of service: oasdiff.com/terms
• Privacy policy: oasdiff.com/privacy