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:
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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:
import Fastify from'fastify';
return { hello:'world' };
fastify.listen({ port:3000 });
vercel dev
});
fastify.get('/',async (request, reply) => {
Vercel Functions
vc deploy
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.
To deploy, connect your Git repository or use Vercel CLI:
More resources
Learn more about deploying Fastify projects on Vercel with the following resources:
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All Vercel Functions limitations apply to the Fastify application, including the standard bundle size limit of 250MB for Node.js applications. Large Functions support Node.js bundles up to 5GB on Fluid compute when enabled (public beta).
Last updated August 10, 2026
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