Why `h3` (from UnJS) Might Replace Express in the Modern Node.js Stack

This content originally appeared on DEV Community and was authored by Alex Aslam

The Express Fatigue is Real

For over a decade, Express.js has been the go-to framework for Node.js backends. But as we scaled our real-time analytics platform to 50,000+ RPS, we hit familiar pain points:

• Middleware soup (unpredictable execution order)
• Performance bottlenecks (slow routing, body-parser overhead)
• Lack of modern features (no built-in WebSockets, HTTP/2)

Then we discovered h3—a lightweight, high-performance alternative from the UnJS ecosystem. After migrating, we saw:

2.5x faster routing
40% less memory usage
Seamless integration with modern tooling

Here’s why h3 might finally dethrone Express.

1. What is h3?

The UnJS Philosophy

h3 is part of the UnJS collection—a suite of modular, framework-agnostic tools designed for:

• Performance (lightweight, minimal overhead)
• Modern JavaScript (ESM-first, TypeScript support)
• Universal compatibility (works in Node.js, Edge, Workers, etc.)

Key Features

Ultra-fast router (no regex-based matching like Express)
Built-in utils (body parsing, cookies, CORS, etc.)
Middleware as composable functions (no next() hell)
Native promise support (zero callback spaghetti)

2. h3 vs Express: Performance Benchmarks

Tested with Node.js 20, 1K concurrent connections

3. Why h3 Feels Like the Future

No More Middleware Chaos

// Express (order-dependent, hard to debug)
app.use(bodyParser());
app.use(cors());
app.use(rateLimiter()); // What runs first?

// h3 (explicit, composable)
const app = createApp();
app.use(
  useCors(),
  useBodyParser(),
  useRateLimiter()
);

Built for Modern JavaScript

// Async/await out of the box
app.use('/api', async (req) => {
  const data = await fetchExternalAPI();
  return { data }; // Auto-handled as JSON
});

Universal Runtime Support

• Node.js
• Edge (Cloudflare, Vercel, Deno)
• Serverless (AWS Lambda, Netlify Functions)

4. When to Switch (And When Not To)

Use h3 If:

You need better performance (high-throughput APIs)
You’re starting a new project (greenfield advantage)
You want modern JS/TS features (ESM, async-first)

Stick with Express If:

You rely on Express middleware (e.g., passport.js)
You have legacy code (migration cost may outweigh benefits)
You need battle-tested stability (Express has 10+ years of fixes)

5. Migration Tips

From Express to h3:

// Before (Express)
app.get('/users/:id', (req, res) => {
  res.json({ user: req.params.id });
});

// After (h3)
const app = createApp();
app.use('/users/:id', (req) => {
  return { user: req.params.id }; // Auto-serialized to JSON
});

Key Differences to Watch For:

• No req/res objects (uses event pattern like Fetch API)
• Middleware are flat functions (no next())
• Built-in body parsing (no body-parser needed)

Key Takeaways

h3 is 2-3x faster than Express in benchmarks
Middleware is simpler (composable functions)
Works everywhere (Node.js, Edge, Serverless)

Is Express finally showing its age? Have you tried h3?

Further Reading

• h3 GitHub
• UnJS Ecosystem

This content originally appeared on DEV Community and was authored by Alex Aslam