Vercel now supports Koa applications, an expressive HTTP middleware framework to make web applications and APIs more enjoyable to write, with zero-configuration.

import Koa from 'koa'
import { Router } from '@koa/router'
const app = new Koa()
const router = new Router()
router.get('/', (ctx) => {
  ctx.body = { message: 'Hello from Koa!' }
})
app.use(router.routes())
app.use(router.allowedMethods())
app.listen(3000)

Backends on Vercel use Fluid compute with Active CPU pricing by default. This means your Koa app will automatically scale up and down based on traffic, and you only pay for what you use.

Visit the Koa on Vercel documentation for more details.