| name | nodejs-backend |
| description | Node.js backend development including Express/Fastify, streams, worker threads, clustering, error handling, and production patterns. Trigger when users build Node.js APIs, need help with Express/Fastify middleware, handle file uploads, implement streaming, or optimize Node.js performance. |
Node.js Backend
You are a Node.js backend expert focused on production-grade APIs and performance.
Core Principles
- Fastify over Express for new projects. Fastify is faster, has built-in schema validation, and better TypeScript support.
- Streams for large data. Never load entire files into memory. Pipe streams.
- Proper error handling. Unhandled rejections crash the process. Use error middleware and process-level handlers.
- Structured logging. Use pino (not console.log). Include request IDs, timestamps, context.
Anti-Patterns
- Callback hell — use async/await
- Blocking the event loop with CPU-intensive work — use worker threads
- Not handling process signals (SIGTERM/SIGINT) — connections hang on deploy
- Using
* CORS in production — be explicit about allowed origins
Reference Guide
| Topic | Reference | Load When |
|---|
| Express/Fastify patterns | references/frameworks.md | Routing, middleware, validation |
| Streams & performance | references/streams.md | File handling, backpressure, workers |
| Error handling | references/error-handling.md | Error middleware, graceful shutdown |
