Never ship a
breaking API change
by accident.

oasdiff turns every API change into a review on your pull request. It's code review, for your API contract. See exactly what changed, approve or reject each change, and block the merge until breaking changes are signed off.

The CLI, GitHub Action, and the shareable side-by-side review are free forever. The approval workflow and audit trail are oasdiff Pro.

Start free trial →GitHub

★ 1.2K GitHub stars · 8M+ downloads · 479 changes detected

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API changes, reviewed like code

oasdiff brings the pull-request review you trust for code to your API contract.

For your codeWith oasdiff
Pull requestAPI change review
Merge checkBreaking-change gate
Approving reviewersAPI approvers
Review historyAPI audit trail

How teams use oasdiff

Works wherever your API lives — local, CI, or the browser.

CLI
# install
brew install oasdiff

# check for breaking changes
oasdiff breaking base.yaml revision.yaml

# generate changelog
oasdiff changelog base.yaml revision.yaml
Install guide →
GitHub Action
# Free: detect breaking changes
- uses: oasdiff/oasdiff-action/breaking@v0
  with:
    base: base.yaml
    revision: revision.yaml

# Pro: post PR comment
- uses: oasdiff/oasdiff-action/pr-comment@v0
  with:
    base: base.yaml
    revision: revision.yaml
    oasdiff-token: ${{ secrets.OASDIFF_TOKEN }}
Action setup →
Web Tool

Paste two OpenAPI specs and get breaking changes, changelog, raw diff, or a side-by-side view — instantly, no install required.

Supports YAML and JSON. Results are processed server-side and not stored.

Open Diff Calculator →

479 API changes detected

Most tools catch a handful of obvious cases. oasdiff detects 479 distinct changes, breaking and non-breaking, covering every way an API modification can affect an existing client, across every part of the OpenAPI spec.

Each change has an ID, severity level, and a detailed description of what changed and why it matters. Results include the exact file and line number of the change.

Browse the full list of changes →
Schema
Types, constraints, enums, required fields, composition
Parameters
Path, query, header, and cookie parameters
Paths & operations
Endpoints, operations, deprecation, sunset
Security
Auth requirements and security schemes
Responses
Status codes and response media types
Request body
Required body and request media types
Headers
Response headers
Components
Reusable schemas and webhooks
Tags
Operation tags
oasdiff Pro

Review, approve, and unblock breaking changes

oasdiff Pro posts a single auto-updating comment on every pull request that touches your API spec — breaking changes at the top, organized by severity, linked to the exact line in the spec.

Each breaking change links to a hosted review page with a side-by-side spec diff. Approve or reject with a comment — the commit status updates automatically, and approvals carry forward when the branch is updated.

See pricing →
oasdiff.com/review/…/my-api/42
API Change Review
my-org/my-api · PR #42 · commit a1b2c3d
⏳ 1 change awaiting review · 1/2 reviewed
🔴GET /users✅

removed the required response property 'email'

✅ Approved by @alice · "intentional migration"
🔴POST /users⏳

removed the required request property 'email'

Used by API teams at

MongoDBStripeLEGOIKEASpotifyMicrosoft

Plus engineers from Adyen, Elastic, Palo Alto Networks, Wiz, HPE, Cvent, Starling Bank, Expedia, Apache Airflow, Cal.com, BeyondTrust, Box, Hitachi, and Hargreaves Lansdown.

OpenAPI 3.0 & 3.1

oasdiff fully supports OpenAPI 3.0 and 3.1 across the diff tool, GitHub Action, PR review, and online service. Upgrade a 3.0 spec to 3.1 online.

Searching for a Swagger diff tool?

Swagger was the original name for what is now the OpenAPI Specification. If your spec file starts with openapi: "3., oasdiff supports it.

Multi-file specs

oasdiff resolves $ref references across files and reports the correct source location for each change, even in complex multi-file API definitions.