Free tool OpenAPI 3.0 OpenAPI 3.1 Swagger 2.0

Detect Breaking Changes in Your OpenAPI Specs

The maintained alternative to Optic — built for modern API teams

Compare two OpenAPI 3.x & Swagger 2.0 specifications side by side. Detect breaking changes, added/removed endpoints, and parameter diffs.

Spec A (base)

1

Spec B (changed)

1

Compare Two OpenAPI Specs

Paste, upload, or fetch two OpenAPI specifications above, then click Compare Specs to see a visual diff with breaking change detection.

Formats
JSON / YAML
Versions
2.0 / 3.x
Cost
Free

Free

Instant diff comparison, no account needed. Paste or upload your specs and compare them right away.

Email Required

Coming soon

Shareable diff links and diff history. Keep track of your API changes over time.

Automatic Tracking

Want automatic version tracking? Publish your API docs for free and get changelog diffs with every update.

Publish docs for free

Need to validate a single spec? Try the OpenAPI Validator →

CI/CDGitHub Marketplace Action

Automate OpenAPI validation and diff checks on every PR.

If this diff view helps during review, enforce the same checks in CI with our GitHub Action. Detect breaking changes, post a PR summary comment, and block bad merges before release.

Compares PR specs against the base branch
Flags breaking changes and validation errors in one job
Public repos are free and unlimited
Install from GitHub Marketplace See full setup guide

Public repository

- uses: apinotes/openapi-validate@v1
  with:
    spec-path: 'openapi.yaml'

Private repository

- uses: apinotes/openapi-validate@v1
  with:
    api-key: ${{ secrets.APINOTES_API_KEY }}
    spec-path: 'openapi.yaml'

Recommended branch protection setup

Enable Require status checks to pass before merging and select your validate job to block invalid or breaking changes.