Fastify

Fastify on Vercel

Last updated October 29, 2025

Fastify is a web framework highly focused on providing the best developer experience with the least overhead and a powerful plugin architecture. You can deploy a Fastify app to Vercel with zero configuration using Vercel Functions.

Fastify applications on Vercel benefit from:

Fluid compute: Pay for the CPU you use, automatic cold start reduction, optimized concurrency, background processing, and more
Preview deployments: Test your changes in a copy of your production infrastructure
Instant Rollback: Recover from breaking changes or bugs in milliseconds
Vercel Firewall: Protect your applications from a wide range of threats with a robust, multi-layered security system
Secure Compute: Create private links between your Vercel-hosted backend and other clouds

Get started with Fastify on Vercel

You can quickly deploy a Fastify application to Vercel by creating a Fastify app or using an existing one:

Deploy Fastify to Vercel

Deploy Live Example

Fastify entrypoint detection

To allow Vercel to deploy your Fastify application and process web requests, your server entrypoint file should be named one of the following:

src/app.{js,mjs,cjs,ts,cts,mts}
src/index.{js,mjs,cjs,ts,cts,mts}
src/server.{js,mjs,cjs,ts,cts,mts}
app.{js,mjs,cjs,ts,cts,mts}
index.{js,mjs,cjs,ts,cts,mts}
server.{js,mjs,cjs,ts,cts,mts}

For example, use the following code as an entrypoint:

src/index.ts

import Fastify from 'fastify'
 
const fastify = Fastify({ logger: true })
 
fastify.get('/', async (request, reply) => {
  return { hello: 'world' }
})
 
fastify.listen({ port: 3000 })

Local development

Use vercel dev to run your application locally

terminal

vercel dev

Minimum CLI version required: 48.6.0

Deploying the application

To deploy, connect your Git repository or use Vercel CLI:

terminal

vc deploy

Minimum CLI version required: 48.6.0

Vercel Functions

When you deploy a Fastify app to Vercel, your Fastify application becomes a single Vercel Function and uses Fluid compute by default. This means your Fastify app will automatically scale up and down based on traffic.