yarn add -D universal-autorouter-hono

// /app.ts
import path from 'node:path'
import { serve } from '@hono/node-server'
import { Hono } from 'hono'
import type { AutoloadRoutesOptions } from 'universal-autorouter'

const app = new Hono()

let autoloadRoutes
// Options of "universal-autorouter" or "universal-autorouter-hono" package
const autoloadRoutesOptions: AutoloadRoutesOptions = {
  // Pattern to scan route files
  pattern: '**/*.ts',
  // Prefix to add to routes
  prefix: '/api',
  // Source directory for route handler files
  routesDir: path.resolve(import.meta.dirname, 'api'),
  // Directories for files used by route handler files (as default scan all files)
  externalDirs: ['utils']
}
if (process.env.NODE_ENV === 'production') {
  ({ default: autoloadRoutes } = await import('universal-autorouter'))
  autoloadRoutesOptions.pattern = '**/*.mjs'
} else {
  ({ default: autoloadRoutes } = await import('universal-autorouter-hono'))
  autoloadRoutesOptions.pattern = '**/*.ts'
  autoloadRoutesOptions.viteDevServer = '<ViteDevServer_INSTANCE>'
  // Example with Vike package
  // autoloadRoutesOptions.viteDevServer = globalThis.__vikeNode!.viteDevServer
}

await autoloadRoutes(app, autoloadRoutesOptions)

const port = +(process.env.PORT || 3000)

serve({
  fetch: app.fetch,
  port
}, () => console.log(`Server running at http://localhost:${port}`))