Hono Routing

Hono Routing & Middleware

Status: Production Ready ✅ Last Updated: 2025-11-21 Dependencies: None (framework-agnostic) Latest Versions: hono@4.12.12, zod@4.3.6, valibot@1.1.0

Quick Start (5 Minutes)

Install

bun add hono@4.12.12  # preferred
# or: bun add hono@4.12.12

Why Hono:

• Fast: Built on Web Standards, runs on any JavaScript runtime
• Lightweight: ~10KB, no dependencies
• Type-safe: Full TypeScript support with type inference
• Flexible: Works on Cloudflare Workers, Deno, Bun, Node.js, Vercel

Basic App

import { Hono } from 'hono'

const app = new Hono()

app.get('/', (c) => {
  return c.json({ message: 'Hello Hono!' })
})

export default app

CRITICAL:

• Use c.json(), c.text(), c.html() for responses
• Return the response (don't use res.send() like Express)
• Export app for runtime

Add Validation

bun add zod@4.3.6 @hono/zod-validator@0.7.4

import { zValidator } from '@hono/zod-validator'
import { z } from 'zod'

const schema = z.object({
  name: z.string(),
  age: z.number(),
})

app.post('/user', zValidator('json', schema), (c) => {
  const data = c.req.valid('json')
  return c.json({ success: true, data })
})

Critical Rules

Always Do

✅ Return responses from handlers (c.json, c.text, c.html, etc.)

✅ Use c.req.valid('source') after validation middleware to get typed data

✅ Export app for deployment (Cloudflare Workers, Bun, Deno, Node.js)

✅ Use validation middleware (zValidator, vValidator) for type-safe request data

✅ Call await next() in middleware to pass control to next handler

✅ Use HTTPException for expected errors (returns proper HTTP status)

✅ Use template tag validators (zValidator, vValidator) not hooks

✅ Define context types for custom variables (Hono<{ Variables: { ... } }>)

✅ Use sub-apps (app.route()) for organizing large APIs

✅ Type your RPC routes (export type AppType = typeof routes) for client

Never Do

❌ Never forget to return response from handlers

❌ Never use req.json() directly without validation - use c.req.valid()

❌ Never mix validation hooks with middleware - use middleware only

❌ Never forget await next() in middleware - breaks middleware chain

❌ Never use res.send() - not available (use c.json(), c.text(), etc.)

❌ Never skip error handling - use app.onError() for global handler

❌ Never access unvalidated data after validation middleware

❌ Never use blocking operations in middleware - breaks async chain

❌ Never hardcode origins in CORS - use environment variables

❌ Never skip type exports for RPC - client won't have types

Top 5 Errors (See references/top-errors.md for all 12)

Error #1: Middleware Response Not Typed

Problem: Middleware returns response but route handler still executes Solution: Don't return from middleware if you want chain to continue - only set variables

// ❌ Wrong - breaks chain
app.use('*', (c) => {
  return c.json({ error: 'Unauthorized' }, 401)
})

// ✅ Correct - throw HTTPException instead
app.use('*', (c, next) => {
  if (!isAuthorized) {
    throw new HTTPException(401, { message: 'Unauthorized' })
  }
  await next()
})

Error #2: Validation Hook vs Middleware Confusion

Problem: Using validation hooks instead of middleware Solution: Always use middleware validators (zValidator, vValidator)

// ❌ Wrong - hooks deprecated
app.post('/user', (c) => {
  const data = c.req.json<User>() // No runtime validation!
})

// ✅ Correct - middleware with runtime validation
app.post('/user', zValidator('json', schema), (c) => {
  const data = c.req.valid('json') // Validated & typed!
})

Error #3: Missing await next() in Middleware

Problem: Middleware doesn't call next(), breaking chain Solution: Always call await next() unless returning early

// ❌ Wrong - chain broken
app.use('*', (c) => {
  console.log('Log')
  // Missing await next()!
})

// ✅ Correct
app.use('*', async (c, next) => {
  console.log('Log')
  await next()
})

Error #4: Context Variable Type Inference

Problem: c.get() and c.set() not typed Solution: Define Variables type in Hono constructor

// ❌ Wrong - no types
const app = new Hono()
c.set('user', { id: '123' }) // Not typed
const user = c.get('user') // any

// ✅ Correct - typed
type Variables = {
  user: { id: string; name: string }
}
const app = new Hono<{ Variables: Variables }>()
c.set('user', { id: '123', name: 'Alice' })
const user = c.get('user') // Fully typed!

Error #5: RPC Type Inference Not Working

Problem: Client doesn't have types from server routes Solution: Export AppType and use hc<AppType>

// Server
const routes = app.get('/users', (c) => c.json([]))
export type AppType = typeof routes // Export this!

// Client
import { hc } from 'hono/client'
import type { AppType } from './server'

const client = hc<AppType>('http://localhost:8787') // Fully typed!

Load references/top-errors.md for all 12 errors with detailed solutions.

Common Use Cases

Use Case 1: Basic REST API

When: Simple CRUD operations Quick Pattern:

app.get('/users', (c) => c.json({ users: [] }))
app.post('/users', (c) => c.json({ created: true }))
app.get('/users/:id', (c) => c.json({ user: {} }))
app.put('/users/:id', (c) => c.json({ updated: true }))
app.delete('/users/:id', (c) => c.json({ deleted: true }))

Load: references/setup-guide.md → Complete Example

Use Case 2: Request Validation (Zod)

When: Need type-safe request validation Quick Pattern:

import { zValidator } from '@hono/zod-validator'
import { z } from 'zod'

app.post('/user',
  zValidator('json', z.object({
    name: z.string(),
    email: z.email(),
  })),
  (c) => {
    const data = c.req.valid('json') // Typed!
    return c.json(data)
  }
)

Load: references/validation-libraries.md

Use Case 3: Type-Safe RPC

When: Full-stack TypeScript with shared types Load: references/rpc-guide.md + templates/rpc-pattern.ts

Use Case 4: Middleware Composition

When: Authentication, logging, rate limiting Load: references/middleware-catalog.md + templates/middleware-composition.ts

Use Case 5: Custom Context Variables

When: Share data between middleware and routes Load: templates/context-extension.ts

When to Load References

Load references/setup-guide.md when:

• User needs complete setup walkthrough
• User asks about deployment to different runtimes
• User needs CRUD API example
• User wants to try alternative validators (Valibot, ArkType, Typia)

Load references/top-errors.md when:

• Encountering any of the 12 documented errors
• User has middleware type issues
• User confused about validation hooks vs middleware
• User needs troubleshooting or debugging

Load references/common-patterns.md when:

• User asks for code examples or best practices
• User needs route grouping, error handling, file upload patterns
• User wants streaming, WebSocket, or pagination examples

Load references/middleware-catalog.md when:

• User needs built-in middleware (cors, logger, jwt, cache, compress, etag)
• User wants to create custom middleware
• User asks about authentication or authorization

Load references/rpc-guide.md when:

• User building full-stack TypeScript app
• User wants type-safe client/server communication
• User asks about hono/client or RPC patterns

Load references/validation-libraries.md when:

• User comparing Zod vs Valibot vs ArkType vs Typia
• User needs validation examples for each library
• User asks about performance or bundle size

Configuration Reference

Minimal Configuration

import { Hono } from 'hono'

const app = new Hono()

app.get('/', (c) => c.json({ message: 'Hello' }))

export default app