Deployment Overview

There are only four real JavaScript server runtimes: Node.js, Bun, Deno, and Cloudflare Workers' workerd. Balda supports the first three. Everything else you'll see called a "supported platform" by other frameworks — Vercel, Netlify, Deno Deploy, Supabase Edge Functions, AWS Lambda, a Service Worker — is a deployment target that runs one of those runtimes underneath, or hands you a Web-standard Request and expects a Response back.

Balda exposes two ways to run:

• server.listen() — starts a real HTTP server on Node, Bun, or Deno. This is what you reach for on any container host: Cloud Run, Fly, Railway, Render, AWS App Runner, a plain VM. No code changes needed for any of these — they just run your Dockerfile.
• server.fetch(request) — a Web-standard fetch(request) => Promise<response> handler, for platforms that hand you a Request directly instead of letting you bind a port. See The fetch() handler.

Support table

Target	Runtime underneath	What you need
Cloud Run, Fly, Railway, Render, App Runner, a VM	Node, Bun, or Deno	Nothing — server.listen() already works
Deno Deploy, Supabase Edge Functions	Deno	Deno.serve(server.fetch)
Vercel Functions (Node runtime), Netlify Functions	Node	export default server.fetch
A Service Worker	—	evt.respondWith(server.fetch(evt.request))
AWS Lambda (API Gateway HTTP API v2 / Function URLs)	Node	handle(server) — see AWS Lambda
AWS Lambda (any event shape)	Node	The AWS Lambda Web Adapter layer, zero code

Cloudflare Workers is not supported

This is the one real runtime balda doesn't run on, and it isn't a small gap: ajv and fast-json-stringify — balda's default validation and serialization path — both compile schemas via new Function, which workerd refuses to run (EvalError: Code generation from strings disallowed for this context). Supporting Workers means compiling schemas ahead of time instead of at route-registration time, which is a change to the validation layer itself, not a deployment adapter. It isn't planned for now.

Caveat: controller autoloading needs a real filesystem

Balda's controllerPatterns option imports controllers by globbing the filesystem at bootstrap. Deno Deploy and Supabase Edge Functions don't give you one. On those targets, register your routes and controllers explicitly instead of relying on autoloading.