Backends on Vercel

Backends deployed to Vercel receive the benefits of Vercel's infrastructure, including:

• Fluid compute: Zero-configuration, optimized concurrency, dynamic scaling, background processing, automatic cold-start prevention, region failover, and more
• Active CPU pricing: Only pay for the CPU you use, not waiting for I/O (e.g. calling AI models, database queries)
• Instant Rollback: Quickly revert to a previous production deployment
• Vercel Firewall: A robust, multi-layered security system designed to protect your applications
• Preview deployments with Deployment Protection: Secure your preview environments and test changes safely before production
• Rolling releases: Gradually roll out backends to detect errors early

Deploy the following backends to Vercel with zero-configuration.

Elysia

Ergonomic framework for humans

Express

Fast, unopinionated, minimalist web framework for Node.js

FastAPI

FastAPI framework, high performance, easy to learn, fast to code, ready for production

Fastify

Fast and low overhead web framework, for Node.js

Flask

The Python micro web framework

H3

Universal, Tiny, and Fast Servers

Hono

Web framework built on Web Standards

Koa

Expressive middleware for Node.js using ES2017 async functions

NestJS

Framework for building efficient, scalable Node.js server-side applications

Nitro

Nitro is a next generation server toolkit.

xmcp

The MCP framework for building AI-powered tools

To process background tasks with Python, you can deploy Celery or Dramatiq workers as queue-triggered Vercel Functions.

If you are transitioning from a fully managed server or containerized environment to Vercel’s serverless architecture, you may need to rethink a few concepts in your application since there is no longer a server always running in the background.

The following are generally applicable to serverless, and therefore Vercel Functions (running with or without Fluid compute).

Vercel Functions can serve WebSocket connections when Fluid compute is enabled. WebSocket connections follow Vercel Function limits, including maximum duration, so clients should handle reconnects when a connection closes.

Store persistent state, rooms, presence, and pub/sub coordination in an external data store instead of relying on in-memory state. Learn more in the WebSockets documentation.

To manage database connections efficiently, use the attachDatabasePool function from @vercel/functions.