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Old Coder API

Old Coder API is an agent skill (a SKILL.md file) from AmazingAng/old-coder. Design, change, or review an HTTP/JSON API surface — endpoints, request/response shapes, authentication and authorization, pagination, idempotency, rate limits, versioning, and deprecations. It works with Claude Code, Codex and Cursor and has 749 GitHub stars.

github.com/AmazingAng/old-coder/skills/old-coder-api (opens in a new tab)

Add this skill

Claude

Claude Code loads skills from ~/.claude/skills/ (all projects) or .claude/skills/ (one project):

git clone --depth 1 https://github.com/AmazingAng/old-coder.git
cp -r old-coder/skills/old-coder-api ~/.claude/skills/old-coder-api   # personal, or .claude/skills in a project

In the Claude apps, zip the old-coder-api 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/AmazingAng/old-coder.git
cp -r old-coder/skills/old-coder-api .agents/skills/old-coder-api   # 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/AmazingAng/old-coder.git
cp -r old-coder/skills/old-coder-api .cursor/skills/old-coder-api   # project; ~/.cursor/skills for all projects

Source (checked Oct 7, 2026): code.claude.com/docs/en/skills (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

Design, change, or review an HTTP/JSON API surface — endpoints, request/response shapes, authentication and authorization, pagination, idempotency, rate limits, versioning, and deprecations. Use when adding or modifying an HTTP endpoint, reviewing an OpenAPI spec or HTTP route diff, or deciding whether an HTTP API change breaks consumers. Do not use as a protocol-compatibility checklist for gRPC/protobuf, GraphQL, WebSockets, or other non-HTTP/JSON interfaces.

When it triggers

  • Use when adding or modifying an HTTP endpoint, reviewing an OpenAPI spec or HTTP route diff, or deciding whether an HTTP API change breaks consumers.
  • use as a protocol-compatibility checklist for gRPC/protobuf, GraphQL, WebSockets, or other non-HTTP/JSON interfaces.

FAQ

Old Coder API FAQ

Still curious? Email info@appsgit.com.

What is the Old Coder API skill?

Old Coder API is an agent skill (a SKILL.md file) from AmazingAng/old-coder. Design, change, or review an HTTP/JSON API surface — endpoints, request/response shapes, authentication and authorization, pagination, idempotency, rate limits, versioning, and deprecations. It works with Claude Code, Codex and Cursor and has 749 GitHub stars. Its SKILL.md lives at github.com/AmazingAng/old-coder/skills/old-coder-api.

How do I install the Old Coder API skill?

Copy the old-coder-api folder (the one containing SKILL.md) into ~/.claude/skills/ for Claude Code, .agents/skills/ for Codex or .cursor/skills/ for Cursor. The agent picks it up automatically when a task matches its description.

Is the Old Coder API skill free?

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

Is Old Coder API maintained?

The repository's most recent commit was on Aug 18, 2026. Its latest release is v0.1.0. appsgit only lists skills from repositories with a commit in the last six months.