Polka — Micro Web Server for Node.js

Introduction

Polka is a micro web server for Node.js that delivers Express-like routing in a tiny footprint. It uses a Trouter-based path matcher for fast route resolution and maintains API compatibility with Express middleware, so existing middleware like cors, helmet, and body-parser work out of the box.

What Polka Does

• Routes HTTP requests with Express-compatible method handlers (get, post, put, delete)
• Resolves routes using Trouter, a lightweight trie-based path matcher
• Supports middleware via .use() with the same (req, res, next) signature as Express
• Handles parameterized routes and wildcard patterns
• Returns a native http.Server, allowing direct access to Node.js server methods

Architecture Overview

Polka wraps Node.js's built-in http.createServer with a thin routing layer. Incoming requests are matched against a trie of registered routes via the Trouter library. Matched handlers execute in sequence with middleware running first. There is no built-in body parser, template engine, or view layer — Polka provides only the router and middleware pipeline, keeping the total package size under 5 KB.

Self-Hosting & Configuration

• Requires Node.js 12 or later
• Install with npm install polka
• Attach middleware with .use() before defining routes
• Call .listen(port) to start; returns a native http.Server instance
• Deploy behind a reverse proxy (Nginx, Caddy) for TLS and load balancing

Key Features

• Under 5 KB total size, with no dependencies beyond Trouter
• Express-compatible middleware signature for ecosystem compatibility
• Trie-based routing is faster than Express's linear route matching
• Returns a standard http.Server for direct integration with Node.js APIs
• Supports async handlers via returned Promises or async functions

Comparison with Similar Tools

• Express — the standard Node.js framework; Polka is 30-50x smaller with faster routing
• Fastify — schema-based validation and plugin system; Polka is simpler and smaller
• Koa — async-first with context objects; Polka keeps the Express req/res signature
• Hono — multi-runtime edge framework; Polka targets Node.js specifically
• uWebSockets.js — C++ backed for raw speed; Polka uses standard Node.js http

FAQ

Q: Can I use Express middleware with Polka? A: Yes. Polka supports the standard (req, res, next) middleware signature, so most Express middleware works without changes.

Q: Does Polka support TypeScript? A: Type definitions are available via @types/polka on npm.

Q: Is Polka suitable for production? A: Yes. Its small surface area and use of native http.Server make it production-ready when paired with a reverse proxy.

Q: How does Polka handle errors? A: Polka provides an onError handler and a onNoMatch handler for 404s. Middleware can call next(err) to trigger error handling.

Sources

• https://github.com/lukeed/polka
• https://github.com/lukeed/polka#readme