Alright, so you’re building an API with Node.js and you're thinking, "Do I just go with Express like everyone else, or should I try out Fastify and see what the hype is about?"

Let’s break it down. I’ve used both, and they both work. But depending on your project, one might make your life way easier than the other.

Express

Express is the old reliable. It’s been around forever, and pretty much every Node developer has used it at some point. If you're looking for something stable with a massive ecosystem, Express is still a solid choice.

Pros

• Huge community. If you run into an issue, someone on Stack Overflow already solved it five years ago.
• Tons of middleware. You need something? There’s probably a package for it.
• Very flexible. It doesn’t force structure or conventions on you.

Cons

• Not the fastest, performance wise.
• Some parts feel a little dated if you’re used to more modern frameworks.
• Lacks builtin support for things like input validation or automatic API docs.

Express example

// express-server.js
const express = require('express');
const app = express();

app.use(express.json());

app.get('/', (req, res) => {
  res.send('Hello from Express');
});

app.listen(3000, () => {
  console.log('Express app running on http://localhost:3000');
});

Easy to understand, works everywhere, no surprises.

Fastify

Fastify is newer, but it's built for performance. If you're starting something fresh and want the benefits of modern architecture, Fastify's got you covered. It's fast, lightweight, and actually pretty nice to work with once you get the hang of it.

Pros

• Way faster than Express in most benchmarks.
• Builtin schema validation using JSON Schema.
• First class TypeScript support.
• Automatic Swagger docs if you want them.

Cons

• Smaller ecosystem. Not every Express middleware has a Fastify version.
• A bit of a learning curve if you're used to Express's "do whatever you want" style.
• Some plugins are still catching up in maturity.

Fastify example

// fastify-server.js
const fastify = require('fastify')({ logger: true });

fastify.get('/', async (request, reply) => {
  return { msg: 'Hello from Fastify' };
});

fastify.listen({ port: 3000 }, (err, address) => {
  if (err) {
    fastify.log.error(err);
    process.exit(1);
  }
  fastify.log.info(`Fastify app running at ${address}`);
});

Feels modern, right? You even get nice JSON logs without having to install anything extra.

So, Which One Should You Use?

Here’s the quick rundown.

Go with Express if:

• You just want to build something quick.
• You or your team already know it well.
• You don’t care too much about performance and just want it to work.

Go with Fastify if:

• You’re starting fresh and want modern features.
• Performance actually matters for your use case.
• You want structured request validation and automatic docs without cobbling together a bunch of packages.

Final Thoughts

Use the right tool for the job. Express is still good, but Fastify is making strong moves. If you're not stuck with legacy code or team constraints, Fastify feels like the better long-term play.

Either way, just build cool stuff.