api-contract-validator
by Timoranjes
Automatically validate OpenAPI specs, detect breaking changes, and sync API implementation with documentation.
- 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
$10
· or 50 creditsSecure 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
- Ready for Cursor
Sample input
Can you check if my recent changes to openapi.yaml introduced any breaking changes and run the spectral linter?
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.
api-contract-validator
by Timoranjes
Automatically validate OpenAPI specs, detect breaking changes, and sync API implementation with documentation.
$10
· or 50 creditsSecure 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
- Ready for Cursor
- Instant install
Sample input
Can you check if my recent changes to openapi.yaml introduced any breaking changes and run the spectral linter?
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
Known Limitations
- Requires existing OpenAPI/Swagger files.
- Dredd integration requires a running local server instance.
- Breaking change detection requires access to the previous spec version.
How to Install
mkdir -p ~/.claude/skills && curl -sL https://www.agensi.io/api/install/api-contract-validator -o /tmp/api-contract-validator.zip && unzip -o /tmp/api-contract-validator.zip -d ~/.claude/skills && rm /tmp/api-contract-validator.zipFree skills install directly. Paid skills require purchase - use the download button above after buying.
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Security Scanned
Passed automated security review
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Compatible with SKILL.md-compatible agents like Claude Code, Cursor, and GitHub Copilot CLI.
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