Express API Design
revfactory/claude-code-harness
Express.js REST API design and implementation guide. An agent skill from revfactory/claude-code-harness.
A skill your agent uses when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable.
Install Express API Design
$ npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a claude-codeProject install by default; add -g for ~/.claude/skills/.
$ gh skill install johnku2011/boilerplates-with-ai-skills express-api-design --agent claude-codeProject scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).
$ git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/boilerplates/express-api/skills/express-api-design .claude/skills/express-api-design && rm -rf skills-srcUse ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.
Claude Code skills documentation · loads skills from .claude/skills/
Install the "express-api-design" agent skill from https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design into .claude/skills/express-api-design/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "express-api-design", then confirm the skill loads.Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$skill-installer install https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-designType this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.
$ npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a codexProject install goes to .agents/skills/; add -g for ~/.codex/skills/.
$ gh skill install johnku2011/boilerplates-with-ai-skills express-api-design --agent codexProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git skills-src && mkdir -p .agents/skills && cp -r skills-src/boilerplates/express-api/skills/express-api-design .agents/skills/express-api-design && rm -rf skills-srcUse ~/.agents/skills/ instead of .agents/skills for a personal install.
Codex skills documentation · loads skills from .agents/skills/
Install the "express-api-design" agent skill from https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design into .agents/skills/express-api-design/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "express-api-design", then confirm the skill loads.Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a cursorProject install goes to .agents/skills/; add -g for ~/.cursor/skills/.
$ gh skill install johnku2011/boilerplates-with-ai-skills express-api-design --agent cursorProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/boilerplates/express-api/skills/express-api-design .cursor/skills/express-api-design && rm -rf skills-srcUse ~/.cursor/skills/ instead of .cursor/skills for a personal install.
Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/
Install the "express-api-design" agent skill from https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design into .cursor/skills/express-api-design/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "express-api-design", then confirm the skill loads.Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gemini skills install https://github.com/johnku2011/boilerplates-with-ai-skills.git --path boilerplates/express-api/skills/express-api-design--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.
$ npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a gemini-cliProject install goes to .agents/skills/; add -g for ~/.gemini/skills/.
$ gh skill install johnku2011/boilerplates-with-ai-skills express-api-design --agent gemini-cliProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/boilerplates/express-api/skills/express-api-design .gemini/skills/express-api-design && rm -rf skills-srcUse ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.
Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/
Install the "express-api-design" agent skill from https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design into .gemini/skills/express-api-design/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "express-api-design", then confirm the skill loads.Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ gh skill install johnku2011/boilerplates-with-ai-skills express-api-designInstalls for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).
$ npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a github-copilotProject install goes to .agents/skills/; add -g for ~/.copilot/skills/.
$ git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git skills-src && mkdir -p .github/skills && cp -r skills-src/boilerplates/express-api/skills/express-api-design .github/skills/express-api-design && rm -rf skills-srcUse ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.
GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/
Install the "express-api-design" agent skill from https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design into .github/skills/express-api-design/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "express-api-design", then confirm the skill loads.GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
$ npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a opencodeOpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.
$ gh skill install johnku2011/boilerplates-with-ai-skills express-api-design --agent opencodeProject scope by default (.agents/skills/); add --scope user for a personal install.
$ git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/boilerplates/express-api/skills/express-api-design .opencode/skills/express-api-design && rm -rf skills-srcUse ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.
OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/
Install the "express-api-design" agent skill from https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design into .opencode/skills/express-api-design/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "express-api-design", then confirm the skill loads.OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.
Facts
- Skill name
express-api-design- GitHub stars
- 240
- Token cost
- ~575 tokens
- SKILL.md length
- 280 words
- Files
- 1
- Skills in repo
- 18
- Repo updated
- First seen
- Licence
- MIT
At a glance
A skill your agent uses when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable.
- Works in 5 steps: Add the route to src/app.js on the app… → Validate and parse input explicitly;… → Return JSON for API routes with a clear… → …
- Changing routes
- SKILL.md covers Overview, Process, Route Design and Middleware Order, plus 4 more sections
- Calls npm
What it does
Express API Design is an agent skill from johnku2011/boilerplates-with-ai-skills. Use when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable.
Its SKILL.md is about 580 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: Express ESM API in this boilerplate
It sits in Backend & APIs, covering API design. It works with Express and Vercel. The licence is MIT.
When your agent uses it
- Changing routes
- Error handling in this Express.js API
- Keep endpoints consistent
Example prompts
- “/express-api-design”
Requirements
- Compatibility (from SKILL.md): Express ESM API in this boilerplate
- Pre-approved tools (allowed-tools): Read
Workflow steps
5 steps, taken from the first numbered list in SKILL.md.
- Add the route to src/app.js on the app returned by createApp().
- Validate and parse input explicitly; never trust request bodies or params.
- Return JSON for API routes with a clear shape and correct status codes
- Centralize error handling with an error-handling middleware; do not leak
- Add a test/ case that starts the app on an ephemeral port and asserts the
What it can do on your machine
Read from SKILL.md and the folder at commit 475dc6a. It shows what the files ask for, not the result of running them.
Tool permissions
Pre-approves these tools, so the agent can use them without asking each time:
Read
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
npm
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md. Its commands use npm, which can reach the network depending on how they are called.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.
Compatibility
Express ESM API in this boilerplate
From compatibility in the SKILL.md frontmatter.
Context cost
Express API Design loads about 575 tokens when it runs. Until then it costs about 41 tokens; SKILL.md has 280 words of instructions outside code blocks.
Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.
Safety
Auto-check passed
The automated check found no risky patterns in SKILL.md.
Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.
SKILL.md
The full file from johnku2011/boilerplates-with-ai-skills at commit 475dc6a, republished under its MIT licence (© johnku2011). 280 words, ~575 tokens.
Download SKILL.mdSave it as
.claude/skills/express-api-design/SKILL.md (or your agent's skills folder).- name
- express-api-design
- description
- Use when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable.
- allowed-tools
- Read
- compatibility
- Express ESM API in this boilerplate
- license
- MIT
- metadata.stack
- express
Express API Design
Overview
Keep the Express app small, testable, and consistent. Build routes on the
exported createApp() factory so they can be tested without binding a port.
Process
- Add the route to
src/app.json the app returned bycreateApp(). - Validate and parse input explicitly; never trust request bodies or params.
- Return JSON for API routes with a clear shape and correct status codes (200/201 success, 400 client error, 404 not found, 500 server error).
- Centralize error handling with an error-handling middleware; do not leak stack traces in responses.
- Add a
test/case that starts the app on an ephemeral port and asserts the response.
Route Design
- Use nouns for resources (
/items,/items/:id), verbs via HTTP methods. - Version breaking changes (
/v2/...) or document compatibility in README. - Document request/response shapes in README or OpenAPI when the surface grows.
Middleware Order
- Security headers / CORS (if needed)
- Body parsers with size limits
- Authentication (if applicable)
- Routes
- 404 handler
- Error handler (last)
Testing
- Integration tests: spin up
createApp()on port0, usefetchagainsthttp://127.0.0.1:<port>/.... - Unit tests: pure functions extracted from handlers.
- Run
npm testbefore every commit.
Guidelines
- Keep handlers thin; move non-trivial logic into small functions you can unit test.
- Prefer explicit routes over broad catch-alls.
- Do not read secrets from the request; read configuration from environment variables at startup.
- Keep responses deterministic and documented in the README.
- Assume stateless serverless when deployed to Vercel — no in-memory sessions.
Deployment
See the shared deploy-vercel skill when shipping to Vercel.
Anti-patterns
- Business logic embedded in anonymous middleware chains.
- Returning raw
error.messageor stacks to clients. - Global mutable state shared across requests in serverless.
© johnku2011, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file
Files
Just SKILL.md in boilerplates/express-api/skills/express-api-design of johnku2011/boilerplates-with-ai-skills.
Open the folder on GitHubat commit 475dc6a
Compare with similar skills
Express API Design next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.
| Skill | Stars | Used in | Tokens | Auto-check | Licence | Repo updated |
|---|---|---|---|---|---|---|
| Express API Design this skilljohnku2011/boilerplates-with-ai-skills | 240 | — | ~575 | Automated safety check: Pass | MIT | |
| Express API Designrevfactory/claude-code-harness | 120 | — | ~276 | Automated safety check: Pass | None | |
| API DesignerJeffallan/claude-skills | 12k | 2 repos | ~2k | Automated safety check: Pass | MIT | |
| Nodejs Backend Patternsever-works/ever-works | 158 | 18 repos | ~4k | Automated safety check: Pass | AGPL-3.0 | |
| cmux Backend Rulesmanaflow-ai/cmux | 28k | 1 repos | ~682 | Automated safety check: Pass | Custom licence | |
| Pangolin CRUD Endpointsfosrl/pangolin | 23k | — | ~461 | Automated safety check: Pass | Custom licence |
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API Designer
Jeffallan/claude-skills
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Nodejs Backend Patterns
ever-works/ever-works
Build production-ready Node.js backend services with Express/Fastify, implementing middleware patterns, error handling, authentication, database integration, and API design best practices.
cmux Backend Rules
manaflow-ai/cmux
Sets the backend TypeScript and Cloud VM rules for cmux: Effect-based services, thin route handlers, Postgres as source of truth, migrations and provider secrets.
Pangolin CRUD Endpoints
fosrl/pangolin
Use whenever asked to add, create, or scaffold a CRUD endpoint, router, or entity in this repo's server (create/list/get/update/delete handlers, new…
API Design Principles
jh941213/my-cc-harness
REST 및 GraphQL API 설계 원칙 가이드. An agent skill from jh941213/my-cc-harness.
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Related
Categories
Questions about Express API Design
What does Express API Design do?
A skill your agent uses when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable. Express API Design is an agent skill from johnku2011/boilerplates-with-ai-skills.js API, to keep endpoints consistent, validated, and testable.
When should I use Express API Design?
Express API Design fits situations like: changing routes; error handling in this Express.js API; keep endpoints consistent.
How do I install Express API Design in Claude Code?
Run `npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a claude-code`. Or copy the skill folder (boilerplates/express-api/skills/express-api-design in johnku2011/boilerplates-with-ai-skills) into .claude/skills/express-api-design in your project. Claude Code loads it when a task matches its description.
How do I install Express API Design in Codex?
Run `npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a codex`. Or copy the skill folder (boilerplates/express-api/skills/express-api-design in johnku2011/boilerplates-with-ai-skills) into .agents/skills/express-api-design in your project. Codex loads it when a task matches its description.
Can I use Express API Design in Cursor, Gemini CLI or GitHub Copilot?
Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add johnku2011/boilerplates-with-ai-skills --skill express-api-design -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/express-api-design, .gemini/skills/express-api-design, .github/skills/express-api-design and .opencode/skills/express-api-design in your project.
What does Express API Design need to run?
Going by SKILL.md and its folder, Express API Design needs the command-line tools its instructions call (npm). Its frontmatter pre-approves these tools: Read. Compatibility (from SKILL.md): Express ESM API in this boilerplate.
Does Express API Design access the network?
SKILL.md contains no URLs. Its commands use npm, which can reach the network depending on how they are called. This is read from the text; nothing was executed.
Is Express API Design safe to install?
Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.
What licence does Express API Design use?
Express API Design is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.
How many tokens does Express API Design use?
About 575 tokens (SKILL.md is roughly 2.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.
What are the alternatives to Express API Design?
Skills that share tags, products or a category with Express API Design: Express API Design (revfactory/claude-code-harness, 120 stars), API Designer (Jeffallan/claude-skills, 12k stars), Nodejs Backend Patterns (ever-works/ever-works, 158 stars) and cmux Backend Rules (manaflow-ai/cmux, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.
Who maintains Express API Design?
johnku2011 (a GitHub user) maintains it in johnku2011/boilerplates-with-ai-skills, which has 240 GitHub stars. The repository holds 18 skills in this directory. The repository was last updated on August 24, 2026.
Source: johnku2011/boilerplates-with-ai-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.