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    api-contract-validator

    by Zicheng Liao

    Automatically validate OpenAPI specs, detect breaking changes, and sync API implementation with documentation.

    Updated May 2026
    Security scanned
    One-time purchase

    $10

    · or 50 credits

    One-time purchase

    30-day refund guarantee

    Secure checkout via Stripe

    Included in download

    • Catch breaking API changes in PRs before merging to main
    • Ensure Express, FastAPI, or Flask code matches the OpenAPI spec
    • terminal automation included
    • Includes example output and usage patterns
    • Instant install

    See it in action

    A real example of what this skill takes in and produces.

    Sample output

    [oasdiff] 2 breaking changes detected in openapi.yaml:

    • Removed property 'user_id' from response body of GET /users/{id}
    • Changed type of 'created_at' from 'string' to 'integer' in schema 'User' [spectral] 1 error: info-contact must be present. Validation failed. Review the diff before merging.

    About This Skill

    What it does

    The API Contract Validator ensures your API implementation stays perfectly in sync with its OpenAPI/Swagger specification. It acts as a guardrail for your API ecosystem, catching schema mismatches, linting errors, and accidental breaking changes before they disrupt your frontend or mobile consumers.

    Why use this skill

    Manually checking that every endpoint, request body, and status code matches a YAML file is error-prone and tedious. This skill automates that process by:

    • Linting: Validating that your spec follows industry standards using Spectral or Redocly.
    • Runtime Checks: Verifying real server responses against the spec using Dredd or language-specific middleware.
    • Diffing: Analyzing changes between spec versions to flag breaking changes like removed fields or changed types.
    • CI/CD Integration: Providing ready-to-use configurations for GitHub Actions and GitLab CI.

    Supported Tools & Frameworks

    It supports the most popular ecosystems out of the box, including Spectral, Redocly, oasdiff, and Dredd. For implementation-specific validation, it provides guidance for Express (Node.js), FastAPI/Flask (Python), and Go. The skill produces actionable reports, JUnit XML for CI pipelines, and markdown diffs that clearly highlight exactly what changed in your API contract.

    Use Cases

    • Catch breaking API changes in PRs before merging to main
    • Ensure Express, FastAPI, or Flask code matches the OpenAPI spec
    • Generate automated contract testing reports for CI/CD gates
    • Identify and fix 'API drift' where documentation lacks actual behavior
    • Bulk-lint OpenAPI specifications for industry best practices

    Reviews

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    Security Scanned

    Passed automated security review

    Permissions

    Terminal / Shell

    Allowed Hosts

    github.com

    File Scopes

    api-contract-validator/**

    Tags

    api-design
    openapi
    testing
    devops
    documentation
    backend

    Creator

    Zicheng Liao

    Frequently Asked Questions

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