contract-tester

Validate API contracts for compatibility and breaking changes.

1|Updated Mar 15, 2026

Search Tags:#api #validation #compatibility #contract #interface

Ready to run

npx skills add https://github.com/blakeox/llm-skills --skill contract-tester-blakeox

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: contract-tester
Source: https://github.com/blakeox/llm-skills/tree/main/openclaw/skills/contract-tester
Command: npx skills add https://github.com/blakeox/llm-skills --skill contract-tester-blakeox

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) and references (resource) components.

What problem does it solve?

Contract Tester ensures that API and interface changes do not break existing consumer integrations, safeguarding backward compatibility.

Core Features & Use Cases

Contract Definition: Clearly defines request and response schemas, including error and event payloads.
Compatibility Analysis: Identifies potential breaking changes by analyzing API surface alterations.
Use Case: Use this Skill to validate that a new version of a REST API remains compatible with client applications before deployment.

Quick Start

Use the contract-tester skill to validate the API contract between the backend and frontend after schema updates.

Frequently Asked Questions about contract-tester

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I check API compatibility to prevent breaking changes in a REST interface?▼

Check API compatibility by analyzing schema modifications against defined request and response contracts. This process identifies potential breaking changes in your API surface before deployment, ensuring new versions remain backward compatible with existing client applications.

What is contract testing for API evolution and when do I need it?▼

Contract testing for API evolution verifies that schema modifications do not introduce compatibility gaps or breaking risks. You need this process during SDK updates, public schema maintenance, and API versioning to safeguard backward compatibility and prevent unintended breaking changes in shared interfaces.

How do I validate that an API update remains compatible with frontend client applications?▼

Validate API updates by defining request and response schemas, including error and event payloads, then analyzing API surface alterations. This compatibility analysis identifies potential breaking changes, ensuring your updated REST API remains fully compatible with frontend client applications before deployment.

Does this API contract validation support error and event payloads?▼

Yes, API contract validation supports error and event payloads. Contract definition clearly defines request and response schemas, including these specific payload types, allowing the compatibility analysis to identify potential breaking changes across all aspects of your public or shared interfaces.

What is the best way to maintain backward compatibility during public schema maintenance?▼

The best way to maintain backward compatibility is through contract compliance checking. By clearly defining schemas and analyzing API surface alterations, you identify potential breaking changes early, ensuring schema modifications do not introduce compatibility gaps during public schema maintenance or SDK updates.

Why does my API schema update introduce breaking risks for existing consumers?▼

API schema updates introduce breaking risks when surface alterations are not validated against existing contracts. Compatibility analysis checks API contracts for compliance, preventing unintended breaking changes in public or shared interfaces by identifying compatibility gaps before deployment.