express-pro

• SKILL.mdcore · 6,826 bytes

## Overview

Express is the minimal, unopinionated web framework for Node.js — routing plus middleware, and deliberately little else. Its power is the middleware pipeline: every request flows through a composable chain you fully control. The flip side is that Express makes no decisions for you — validation, auth, structure, and security are all yours. This skill covers building Express services that stay maintainable and safe, from middleware design to production hardening.

## When to use

- Building a REST API, webhook receiver, or lightweight service on Node.
- Structuring middleware (auth, logging, validation, error handling) correctly.
- Hardening an existing Express app (headers, rate limiting, input validation).
- Debugging middleware ordering bugs or "headers already sent" errors.
- Choosing between Express and heavier frameworks (NestJS, Fastify, Hono).
- Adding SSE or streaming responses to a Node service.
- Migrating an Express 4 app to Express 5.