API Contract Diff Checker

Private multi-contract review

Compare OpenAPI, AsyncAPI or GraphQL versions and explain breaking changes locally.

Contract format

Baseline contract

The last released or accepted contract.

Current contract

The candidate contract to review.

openapi: 3.1.0
info: { title: Pet API, version: 2.0.0 }
paths:
  /pets/{id}:
    get:
      summary: Get one pet
      security: [{ bearerAuth: [] }]
      parameters:
        - { name: id, in: path, required: true, schema: { type: integer } }
        - { name: locale, in: query, required: true, schema: { type: string } }
      responses:
        '200':
          description: Pet
          content: { application/json: { schema: { $ref: '#/components/schemas/Pet' } } }
  /pets:
    post:
      requestBody:
        required: true
        content: { application/json: { schema: { $ref: '#/components/schemas/PetInput' } } }
      responses: { '201': { description: Created } }
components:
  securitySchemes: { bearerAuth: { type: http, scheme: bearer } }
  schemas:
    Pet:
      type: object
      required: [id, name]
      properties: { id: { type: string }, name: { type: string }, status: { type: string, enum: [active, pending] } }
    PetInput:
      type: object
      required: [name]
      properties: { name: { type: string } }

How to use it

01
Load both contracts
Paste or open a baseline and current OpenAPI, AsyncAPI or GraphQL contract.
02
Review compatibility
Inspect operation, input, response, security and schema changes with before and after evidence.
03
Plan the release
Mark reviewed exceptions and export a changelog, audit data or CI decision.

Frequently asked questions

Are API contracts uploaded?

No. Parsing, normalization, comparison and export run in this browser.

Which contracts are supported?

OpenAPI 3.x, common AsyncAPI 2 and 3 structures, and GraphQL SDL are supported.

Does this replace contract tests?

No. Static contract comparison is an early review layer; runtime validators and consumer tests remain necessary.

Are external references fetched?

No. Local component references are resolved where supported; remote references are reported as a review boundary.

Keep working with other focused browser utilities.

All tools

How to use it

Load both contracts

Review compatibility

Plan the release

Frequently asked questions

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