Overview
api-designer is an open-source backend skill for Claude Code and compatible agents, published by Jeffallan. Its author describes it as: “Use when designing REST or GraphQL APIs, creating OpenAPI specifications, or planning API architecture. Invoke for resource modeling, versioning strategies, pagination patterns, error handling standards.”. The project has 11k stars on GitHub and is available under the MIT license. Add it to your setup with `/plugin marketplace add Jeffallan/claude-skills`.
What api-designer does
Senior API architect specializing in REST and GraphQL APIs with comprehensive OpenAPI 3.1 specifications.
Best for
What’s inside
The SKILL.md for api-designer is organised into these sections:
- Core Workflow
- Reference Guide
- Constraints
- MUST DO
- MUST NOT DO
- Templates
- OpenAPI 3.1 Resource Endpoint (copy-paste starter)
- RFC 7807 Error Response (copy-paste)
- Output Checklist
- Knowledge Reference
Installation
Add api-designer to your agent with:
/plugin marketplace add Jeffallan/claude-skillsReview a skill’s source before installing it — skills can instruct your agent to run commands. This command comes from the skill’s public repository, which is the source of truth for setup steps. New to skills? Read how to install Claude Code skills.
Supported agents
- Claude Code — ships a claude code plugin marketplace
License
api-designer is published under the MIT license.
Strengths
- Clear MIT license — safe to read and adapt within its terms
- Ships in Jeffallan/claude-skills, an established project with 11,060 GitHub stars
- Works with Claude Code
- Actively maintained — repository updated in the last 90 days
Author
Topics
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Frequently asked questions
- What does api-designer do?
- Use when designing REST or GraphQL APIs, creating OpenAPI specifications, or planning API architecture. Invoke for resource modeling, versioning strategies, pagination patterns, error handling standards.
- How do I install api-designer?
- Run /plugin marketplace add Jeffallan/claude-skills in your agent, then reload your skills. Review the source at https://github.com/Jeffallan/claude-skills before installing.
- Is api-designer free to use?
- Yes. api-designer is free and open source under the MIT license, so you can read, run, and adapt it within that license's terms.
- Which agents does api-designer work with?
- api-designer lists Claude Code — named in its SKILL.md, its plugin marketplace or its repository topics. Skills use the portable SKILL.md format, so other agents that read that format may load it too.
- Where does api-designer come from?
- api-designer ships inside Jeffallan/claude-skills, a repository that contains 41 catalogued skills in total. The repository's 11,060 GitHub stars apply to that whole collection, not to this skill on its own.