Every added, removed, deprecated and breaking change, grouped Keep a Changelog style and ready to ship as Markdown, JSON, or a live documentation page.
11Add both spec versions above, then click Generate Changelog. You'll get grouped, human-readable release notes — and can download them as Markdown, JSON, or publish them as HTML docs.
Publish your API docs on ApiNotes and every spec upload is diffed against the previous version — the changelog writes itself, versioned, hosted, and linked from your docs. No copy-paste, no forgetting.
Need the raw diff instead? Try the OpenAPI Diff tool →· Validating a single spec? OpenAPI Validator →
HTML documentation (live ApiNotes docs with the changelog already populated, which you can claim and keep permanently), Markdown (a Keep a Changelog style CHANGELOG.md), and JSON (a structured release entry with grouped sections).
OpenAPI 3.0, 3.1, 3.2 and Swagger 2.0, in both JSON and YAML. The two versions you compare don't have to use the same format.
Generating release notes stores nothing — the diff runs and the result is returned. Only when you choose to publish HTML documentation is a temporary project created, and it is deleted automatically after 48 hours.
The same engine that powers our OpenAPI diff: removed endpoints, removed or newly required parameters and properties, narrowed types, changed security requirements and removed responses all count as breaking.