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Express → Fastify

medium

2x faster throughput, built-in validation with JSON Schema, TypeScript-first. Plugin system > middleware chain.

Estimated: 4-12h · 6 steps
Progress0%
Step 1: Install Fastify
npm install fastify @fastify/cors @fastify/helmet && npm uninstall express
Step 2: Rewrite server entry

Replace app = express() with Fastify({ logger: true }). Register plugins instead of app.use().

import Fastify from 'fastify'
const app = Fastify({ logger: true })
Step 3: Convert routes

app.get('/path', (req, res) => ...) → app.get('/path', async (request, reply) => ...). Note: reply not res.

Step 4: Add validation schemas

Replace express-validator/joi with JSON Schema on route level. Fastify validates automatically.

Step 5: Replace middleware

body-parser → built-in. cors → @fastify/cors. helmet → @fastify/helmet. multer → @fastify/multipart.

Step 6: Test
✓ All API endpoints return correct responses. Benchmark shows throughput improvement.

What this migration involves

Moving from Express to Fastify is rated medium and takes about 4-12h on a typical project. The guide breaks it into 6 steps, 2 of which ship with runnable commands and 1 with a verification check. On pricing, Express is open-source and Fastify is open-source with a free plan to test the move.

Express data →Fastify data →

Related migrations

Express → Hono — easy, 2-4hExpress → Elysia (Bun) — medium, 4-10h

FAQ

How long does migrating from Express to Fastify take?

Around 4-12h for a typical project — 6 steps, difficulty rated medium, 2 of them with copy-paste commands.

Is moving from Express to Fastify reversible?

No reverse guide is tracked yet, so treat this as a one-way move and keep a full export of your Express data before you start.

What does Fastify cost compared to Express?

Express: open-source from $0/mo, free plan available. Fastify: open-source from $0/mo, free plan available.