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API And Interface Design

API And Interface Design is an agent skill (a SKILL.md file) from addyosmani/agent-skills. Guides stable API and interface design. Use when designing APIs, module boundaries, or any public interface. It works with Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode and has 110,586 GitHub stars across a repository of 13 listed skills.

github.com/addyosmani/agent-skills/skills/api-and-interface-design (opens in a new tab)

Data as of from the GitHub API and skills.sh; description from the skill's SKILL.md. Report an error

View on GitHub (opens in a new tab)View on skills.sh (opens in a new tab)

Add this skill

Claude

This repository is a Claude Code plugin marketplace. In Claude Code:

/plugin marketplace add addyosmani/agent-skills
/plugin install agent-skills@addy-agent-skills

In the Claude apps, zip the api-and-interface-design folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

ChatGPT / Codex

Codex reads skills from .agents/skills/ in a repo or ~/.agents/skills/ for every project:

git clone --depth 1 https://github.com/addyosmani/agent-skills.git
cp -r agent-skills/skills/api-and-interface-design .agents/skills/api-and-interface-design   # repo; ~/.agents/skills for all projects

Standalone skills also load in the ChatGPT desktop app.

Cursor

Cursor loads skills from .cursor/skills/ (or ~/.cursor/skills/) and also reads .claude/skills/:

git clone --depth 1 https://github.com/addyosmani/agent-skills.git
cp -r agent-skills/skills/api-and-interface-design .cursor/skills/api-and-interface-design   # project; ~/.cursor/skills for all projects

Source (checked Oct 7, 2026): code.claude.com/docs/en/skills (opens in a new tab), code.claude.com/docs/en/plugin-marketplaces (opens in a new tab), support.claude.com/en/articles/12512180-using-skills-in-claude (opens in a new tab), learn.chatgpt.com/docs/build-skills (opens in a new tab), cursor.com/docs/context/skills (opens in a new tab)

What this skill does

Guides stable API and interface design. Use when designing APIs, module boundaries, or any public interface. Use when creating REST or GraphQL endpoints, defining type contracts between modules, or establishing boundaries between frontend and backend. Design stable, well-documented interfaces that are hard to misuse. Good interfaces make the right thing easy and the wrong thing hard.

When it triggers

  • Use when designing APIs, module boundaries, or any public interface.
  • Use when creating REST or GraphQL endpoints, defining type contracts between modules, or establishing boundaries between frontend and backend.

More skills in addyosmani/agent-skills

13 skills are listed from this repository.

Similar skills

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All Design & frontend

FAQ

API And Interface Design FAQ

Still curious? Email info@appsgit.com.

How do I install the API And Interface Design skill?

In Claude Code, run /plugin marketplace add addyosmani/agent-skills and then /plugin install agent-skills@addy-agent-skills. For Codex or Cursor, copy the api-and-interface-design folder into .agents/skills/ or .cursor/skills/.

Is the API And Interface Design skill free?

Yes. The repository is open source under the MIT license.

Is API And Interface Design maintained?

The repository's most recent commit was on Oct 13, 2026. Its latest release is 0.6.13. appsgit only lists skills from repositories with a commit in the last six months.