OpenAPI and Swagger diff, in your browser

This is the online version of oasdiff, an open-source tool for comparing OpenAPI specifications. Paste or upload two specs to see every change side by side and find the ones that break existing clients, then export the report as text, YAML, JSON, Markdown, or HTML. The same engine runs as a CLI and a GitHub Action, so you can diff specs automatically on every pull request.

Frequently asked questions

What is an OpenAPI diff?

An OpenAPI diff compares two versions of an OpenAPI (or Swagger) specification and reports what changed between them: added, removed, and modified endpoints, parameters, schemas, and responses. oasdiff runs the comparison and marks which changes are breaking for existing API clients.

Does this work with Swagger files?

Yes. Swagger is the former name of the OpenAPI Specification, so a Swagger diff and an OpenAPI diff are the same thing. This tool supports OpenAPI 3.0, 3.1 and 3.2 specs in YAML or JSON.

How do I find breaking changes between two API specs?

Pick the Breaking Changes mode, paste or upload the old and new spec, and generate. oasdiff lists every change that would break existing clients, such as a removed endpoint, a newly required parameter, or a narrowed type.

Is it free, and do I need to install anything?

It is free and runs entirely in your browser with no install and no sign-up. For diffs on every pull request, the same engine is available as an open-source CLI and GitHub Action.

What output formats are supported?

You can export the diff, changelog, or breaking-changes report as text, YAML, JSON, Markdown, or HTML.