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API Designer

Designs REST/GraphQL APIs end to end — resource modeling, OpenAPI 3.1 specs, error standards, and versioning strategy.

Web & APIIntermediate★ 11,661⑂ 1,123AI score 8/10Last updated: Aug 7, 2026

What it does

  • Runs a 6-step workflow: analyze domain → model resources → design endpoints → write the OpenAPI 3.1 contract → mock and verify → plan versioning/deprecation.
  • Ships copy-paste templates: cursor pagination, RFC 7807 Problem Details errors (application/problem+json), Bearer JWT security scheme.
  • Enforces validation with npx @redocly/cli lint openapi.yaml and contract testing with npx @stoplight/prism-cli mock openapi.yaml.
  • States explicit MUST / MUST NOT rules: no verbs in URIs, consistent response shapes, pagination on every collection, documented rate limits.

Who it's for

  • Backend engineers and architects designing a new API surface.
  • Tech leads standardizing error formats, versioning policy, and pagination across a team.
  • Anyone documenting an existing API as OpenAPI for SDK or client generation.

Example uses

  1. "Design a REST API for orders and payments" → resource table, endpoint list, OpenAPI 3.1 YAML, and a full error catalog.
  2. "Add fields to our v1 API without breaking clients" → deprecation policy plus a migration path.
  3. "Convert this list endpoint to cursor pagination" → next_cursor/has_more schema with 400/401/429 responses wired in.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/Jeffallan/claude-skills/HEAD/skills/api-designer/SKILL.md

What I want: (describe your task here)

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↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
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Install in Claude Code

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Install the skill I found on Claude Skill Mart.
Copy the skills/api-designer folder from the GitHub repo Jeffallan/claude-skills into my ~/.claude/skills/api-designer/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/Jeffallan/claude-skills.git /tmp/claude-skills && mkdir -p ~/.claude/skills && cp -r /tmp/claude-skills/skills/api-designer ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Open a terminal and clone the repo: git clone https://github.com/Jeffallan/claude-skills.git
  2. Create the skills directory: mkdir -p ~/.claude/skills
  3. Copy just this skill: cp -r claude-skills/skills/api-designer ~/.claude/skills/
  4. Verify with ls ~/.claude/skills/api-designer that SKILL.md and the references/ folder came along.
  5. Install Node.js (which provides npx) if you want the lint and mock-server steps to run.
  6. Restart Claude Code and prompt something like "design an OpenAPI 3.1 spec for a users API" to trigger the skill.
View source on GitHub ↗License: MIT