Express Api Design

Community

johnku2011

express-api-design

Use when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable.

Overview

Publisher	johnku2011
Repository	`boilerplates-with-ai-skills`
Skill name	`express-api-design`
Stars	239
Forks	24
Bundled files	Instructions only
License	MIT
Links	Skill source Repository Homepage

Markdown instructions
A SKILL.md file the model loads on demand, so it only costs tokens when a request actually matches.
Works with any LLM
AI skills are plain Markdown, not provider-specific code, so this works with GPT, Claude, Gemini, Grok, or a local model.
Self-contained
Everything the model needs lives in the instructions — no extra files to sync.
Open source
Published by johnku2011 on GitHub. Read the source before you install it.

Installation

Install the Express Api Design AI skill in TypingMind to use it with any LLM, or drop it into another agent that reads SKILL.md.

Install in TypingMind

TypingMind installs a skill straight from its GitHub folder — it reads SKILL.md, bundles the resource files, and stores the result locally.

Open the app and go to Plugins → Skills.
Choose "Install from GitHub".
Paste the skill folder URL below and confirm.
https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design
Enable the skill in any chat where you want it available.

Store

Installed

Skills

Add skills

Import one or more skills from a public GitHub folder or a local .skill or .zip archive, or SKILL.md file.

From GitHub URLFrom .skill, .zip, or SKILL.md

GitHub repo or folder

https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design

Points to a single skill folder, or any folder that contains multiple skills. Public repos only.

CancelContinue

Plugins → Skills → Add skill → From GitHub URL, then paste the folder URL and press Continue.

Install in another agent

Any agent that reads the Agent Skills format can use this skill — copy the folder into that agent's skills directory.

Claude Code — .claude/skills

git clone --depth 1 https://github.com/johnku2011/boilerplates-with-ai-skills.git /tmp/boilerplates-with-ai-skills
mkdir -p .claude/skills
cp -r /tmp/boilerplates-with-ai-skills/boilerplates/express-api/skills/express-api-design .claude/skills/express-api-design

Restart Claude Code after copying so it picks up the new skill.

Use it in TypingMind

Enable Express Api Design in any TypingMind chat and the model takes it from there. Its name and description sit in the system prompt, and the moment a request matches, the model loads the full instructions itself — you never invoke it by hand, and it costs no tokens until it is actually used.

The model loads Express Api Design on its own as soon as a request matches it.

Works with any AI model

AI skills are plain Markdown instructions rather than provider-specific code, so Express Api Design is not tied to the model it was written for. Install it once in TypingMind and use it with GPT-5, Claude, Gemini, Grok, DeepSeek, Mistral, Llama, or a local model you run yourself — all on your own API keys.

Loaded only when it is needed
The system prompt carries just the name and description. The instructions are fetched on the first matching request, so an idle skill costs nothing.
Switch models mid-chat
Because the skill is instructions rather than code, changing model does not break it — the next model reads the same SKILL.md.

Skill instructions

This is the SKILL.md content the model loads. Read it before installing — a skill is instructions your model will follow.

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.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 (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 port 0, use fetch against http://127.0.0.1:<port>/....
Unit tests: pure functions extracted from handlers.
Run npm test before 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.message or stacks to clients.
Global mutable state shared across requests in serverless.

Frequently asked questions

What does the Express Api Design AI skill do?

Use when adding or changing routes, middleware, or error handling in this Express.js API, to keep endpoints consistent, validated, and testable.

Why use Express Api Design on TypingMind?

Because you install it once and use it with any model. Express Api Design is plain Markdown rather than provider-specific code, so the same skill runs on GPT-5, Claude, Gemini, Grok, or a local model — and you can switch model mid-chat without it breaking. TypingMind runs on your own API keys, so you pay providers directly instead of a per-seat subscription, and your skills and chats stay in your own storage.

How do I install Express Api Design in TypingMind?

Open Plugins → Skills → Install from GitHub in TypingMind and paste https://github.com/johnku2011/boilerplates-with-ai-skills/tree/main/boilerplates/express-api/skills/express-api-design. TypingMind reads its SKILL.md and installs it as a skill you can enable per chat.

Which AI models can use Express Api Design?

Any model you connect in TypingMind. AI skills are plain Markdown instructions rather than provider-specific code, so GPT, Claude, Gemini, Grok, and local models can all load this skill when a request matches it.

How many AI models can I use with Express Api Design?

As many as you like. As long as a model supports skills, you can use Express Api Design with it — GPT, Claude, Gemini, Grok, DeepSeek, Mistral, Llama and more — all on TypingMind with your own API keys.

Is the Express Api Design AI skill free?

Yes. It is published on GitHub by johnku2011 under the MIT license. You only pay your own AI provider for the tokens you use.

What are AI skills?

An AI skill is a reusable instruction bundle that teaches an AI model how to do one specific task. It follows the open Agent Skills format: a SKILL.md file with a name and description, plus any scripts, templates or reference files the model may need. The model reads the instructions only when your request matches the skill, so an installed skill costs nothing until it is used.

How are AI skills different from plugins or MCP servers?

A plugin or MCP server gives a model new tools to call — code that runs somewhere and returns a result. An AI skill gives the model knowledge and process instead: how to approach a task, which steps to follow, what good output looks like. Skills are plain Markdown, so they need no server, no API key and no runtime, and they work with any model.

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Overview

Installation

Install in TypingMind

Install in another agent

Use it in TypingMind

Works with any AI model

Skill instructions

Express API Design

Overview

Process

Route Design

Middleware Order

Testing

Guidelines

Deployment

Anti-patterns

Frequently asked questions

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