Mono Repo Deployment on Vercel Hono & Orpc

[arpitjacob]

I've been trying to deploy the backend server on vercel, I am using https://better-t-stack.dev/new to scaffold the project. But running into all kinds of weird errors. Is there an example of using hono & orpc that deploys on vercel

[dosubot[bot]]

Hi @arpitjacob! I'm Dosu and I’m helping the orpc team.

There isn't an official example or dedicated documentation for deploying a Hono & orpc backend on Vercel, especially in a monorepo setup. However, it is possible with the right configuration. The main pitfalls are TypeScript type inference issues across monorepo boundaries—these can break both local dev and Vercel builds. Make sure your frontend's tsconfig.json has a correct path mapping to the backend's type definitions, and that your build pipeline ensures backend types are built before the frontend. You may need to tweak your Vercel build steps to guarantee this order [discussion].

There are trade-offs between using Hono (middleware, helpers, but more abstraction and overhead) and using orpc standalone (minimal, faster, but you handle things like cookies yourself) [discussion].

You can look at the Next.js playground in the orpc repo for patterns on API handler setup, and there's a basic Vercel config for clean URLs [vercel config PR], but nothing Hono-specific. If you share the specific errors you're seeing, I can help troubleshoot more directly.

To reply, just mention @dosu.

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[unnoq]

I need more information to help troubleshoot this issue. Could you provide:

• How are you deploying your project?
• Which part specifically isn't working - Hono or oRPC?
• Have you successfully deployed similar projects to Vercel before?

A minimal reproduction example would also be very helpful if possible.

[unnoq]

The config "moduleResolution": "bundler", is recommended when using to combine with a bundler while tsc is not

[arpitjacob]

@unnoq just tried it running into the same issues, updated the repo

https://github.com/arpitjacob/mono-nextjs-orpc-hono

[arpitjacob]

managed to fix the serverless functions crashing by adding the .js file extension

• If you are using "type": "module" in your package. json, you must include the file
extension:
Ts ts • Apply to index.ts
import {... 3 from './lib/auth.js'
(Or use a build tool that rewrites these for you.)

but now API is throwing 404. I am guessing its a config issue now. works fine locally.

[arpitjacob]

Got it working
had to set the basepath

const app = new Hono().basePath("/api");

Change
prefix: "/api/rpc",

add output to `vercel.json.
"outputDirectory": "./dist",