hono

name	hono
description	Use when building Hono web applications deployed to Vercel, or when the user asks about Hono APIs, routing, middleware, JSX, validation, testing, or streaming. TRIGGER when code imports from 'hono' or 'hono/*', or user mentions Hono. Use `npx hono request` to test endpoints.

Hono Skill

Build Hono web applications and deploy them to Vercel with zero configuration. This skill provides inline API knowledge for AI. Use npx hono request to test endpoints. If the hono-docs MCP server is configured, prefer its tools for the latest documentation over the inline reference.

Hono CLI Usage

Request Testing

Test endpoints without starting an HTTP server. Uses app.request() internally.

# GET request
npx hono request [file] -P /path

# POST request with JSON body
npx hono request [file] -X POST -P /api/users -d '{"name": "test"}'

Note: Do not pass credentials directly in CLI arguments. Use environment variables for sensitive values.

---

Deploying Hono on Vercel

Hono apps deploy to Vercel with zero configuration. Your server routes automatically become Vercel Functions using Fluid compute by default.

File Placement

Export your Hono app as the default export from any of these locations:

• app.{js,cjs,mjs,ts,cts,mts}
• index.{js,cjs,mjs,ts,cts,mts}
• server.{js,cjs,mjs,ts,cts,mts}
• src/app.{js,cjs,mjs,ts,cts,mts}
• src/index.{js,cjs,mjs,ts,cts,mts}
• src/server.{js,cjs,mjs,ts,cts,mts}

import { Hono } from 'hono'

const app = new Hono()
// ... routes ...
export default app

No Node.js adapter (@hono/node-server) is needed for Vercel — just use the default export. Use @hono/node-server only for local development if not using vc dev.

Local Development

Use Vercel CLI to run locally with the same behavior as production:

vc dev

Static Assets

Place static files in the public/ directory. They are served via the Vercel CDN with default headers.

Important: Hono's serveStatic() is ignored on Vercel — use the public/ directory instead.

Streaming

Vercel Functions support streaming, which works with Hono's stream(), streamText(), and streamSSE() helpers out of the box.

Middleware: Hono vs Vercel

• Hono Middleware — Runs inside your app before route handlers (CORS, auth, logging, etc.)
• Vercel Routing Middleware — Runs at the edge before your app is invoked (rewrites, redirects, headers). See Vercel Routing Middleware docs.

Both can be used together.

---

Hono API Reference

App Constructor

import { Hono } from 'hono'

const app = new Hono()

// With TypeScript generics for request-scoped variables
type Env = {
  Variables: { user: User }
}
const app = new Hono<Env>()

Routing Methods

app.get('/path', handler)
app.post('/path', handler)
app.put('/path', handler)
app.delete('/path', handler)
app.patch('/path', handler)
app.options('/path', handler)
app.all('/path', handler) // all HTTP methods
app.on('PURGE', '/path', handler) // custom method
app.on(['PUT', 'DELETE'], '/path', handler) // multiple methods

Routing Patterns

// Path parameters
app.get('/user/:name', (c) => {
  const name = c.req.param('name')
  return c.json({ name })
})

// Multiple params
app.get('/posts/:id/comments/:commentId', (c) => {
  const { id, commentId } = c.req.param()
})

// Optional parameters
app.get('/api/animal/:type?', (c) => c.text('Animal!'))

// Wildcards
app.get('/wild/*/card', (c) => c.text('Wildcard'))

// Regexp constraints
app.get('/post/:date{[0-9]+}/:title{[a-z]+}', (c) => {
  const { date, title } = c.req.param()
})

// Chained routes
app
  .get('/endpoint', (c) => c.text('GET'))
  .post((c) => c.text('POST'))
  .delete((c) => c.text('DELETE'))

Route Grouping

// Using route()
const api = new Hono()
api.get('/users', (c) => c.json([]))

const app = new Hono()
app.route('/api', api) // mounts at /api/users

// Using basePath()
const app = new Hono().basePath('/api')
app.get('/users', (c) => c.json([])) // GET /api/users

Error Handling

app.notFound((c) => c.json({ message: 'Not Found' }, 404))

app.onError((err, c) => {
  console.error(err)
  return c.json({ message: 'Internal Server Error' }, 500)
})

---

Context (c)

Response Methods

c.text('Hello') // text/plain
c.json({ message: 'Hello' }) // application/json
c.html('<h1>Hello</h1>') // text/html
c.redirect('/new-path') // 302 redirect
c.redirect('/new-path', 301) // 301 redirect
c.body('raw body', 200, headers) // raw response
c.notFound() // 404 response

Headers & Status

c.status(201)
c.header('X-Custom', 'value')
c.header('Cache-Control', 'no-store')

Variables (request-scoped data)

// In middleware
c.set('user', { id: 1, name: 'Alice' })

// In handler
const user = c.get('user')
// or
const user = c.var.user

Environment Variables

On Vercel, use process.env to access environment variables:

const apiKey = process.env.API_KEY

Renderer

app.use(async (c, next) => {
  c.setRenderer((content) =>
    c.html(
      <html><body>{content}</body></html>
    )
  )
  await next()
})

app.get('/', (c) => c.render(<h1>Hello</h1>))

---

HonoRequest (c.req)

c.req.param('id') // path parameter
c.req.param() // all path params as object
c.req.query('page') // query string parameter
c.req.query() // all query params as object
c.req.queries('tags') // multiple values: ?tags=A&tags=B → ['A', 'B']
c.req.header('Authorization') // request header
c.req.header() // all headers (keys are lowercase)

// Body parsing
await c.req.json() // parse JSON body
await c.req.text() // parse text body
await c.req.formData() // parse as FormData
await c.req.parseBody() // parse multipart/form-data or urlencoded
await c.req.arrayBuffer() // parse as ArrayBuffer
await c.req.blob() // parse as Blob

// Validated data (used with validator middleware)
c.req.valid('json')
c.req.valid('query')
c.req.valid('form')
c.req.valid('param')

// Properties
c.req.url // full URL string
c.req.path // pathname
c.req.method // HTTP method
c.req.raw // underlying Request object

---

Middleware

Using Built-in Middleware

import { cors } from 'hono/cors'
import { logger } from 'hono/logger'
import { basicAuth } from 'hono/basic-auth'
import { prettyJSON } from 'hono/pretty-json'
import { secureHeaders } from 'hono/secure-headers'
import { etag } from 'hono/etag'
import { compress } from 'hono/compress'
import { poweredBy } from 'hono/powered-by'
import { timing } from 'hono/timing'
import { cache } from 'hono/cache'
import { bearerAuth } from 'hono/bearer-auth'
import { jwt } from 'hono/jwt'
import { csrf } from 'hono/csrf'
import { ipRestriction } from 'hono/ip-restriction'
import { bodyLimit } from 'hono/body-limit'
import { requestId } from 'hono/request-id'
import { methodOverride } from 'hono/method-override'
import { trailingSlash, trimTrailingSlash } from 'hono/trailing-slash'

// Registration
app.use(logger()) // all routes
app.use('/api/*', cors()) // specific path
app.post('/api/*', basicAuth({ username: 'admin', password: 'secret' }))

Custom Middleware

// Inline
app.use(async (c, next) => {
  const start = Date.now()
  await next()
  const elapsed = Date.now() - start
  c.res.headers.set('X-Response-Time', `${elapsed}ms`)
})

// Reusable with createMiddleware
import { createMiddleware } from 'hono/factory'

const auth = createMiddleware(async (c, next) => {
  const token = c.req.header('Authorization')
  if (!token) return c.json({ error: 'Unauthorized' }, 401)
  await next()
})

app.use('/api/*', auth)

Middleware Execution Order

Middleware executes in registration order. await next() calls the next middleware/handler, and code after next() runs on the way back:

Request → mw1 before → mw2 before → handler → mw2 after → mw1 after → Response

app.use(async (c, next) => {
  // before handler
  await next()
  // after handler
})

---

Validation

Validation targets: json, form, query, header, param, cookie.

Zod Validator

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

const schema = z.object({
  title: z.string().min(1),
  body: z.string()
})

app.post('/posts', zValidator('json', schema), (c) => {
  const data = c.req.valid('json') // fully typed
  return c.json(data, 201)
})

Valibot / Standard Schema Validator

import { sValidator } from '@hono/standard-validator'
import * as v from 'valibot'

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

app.post('/users', sValidator('json', schema), (c) => {
  const data = c.req.valid('json')
  return c.json(data, 201)
})

---

JSX

Setup

In tsconfig.json:

{
  "compilerOptions": {
    "jsx": "react-jsx",
    "jsxImportSource": "hono/jsx"
  }
}

Or use pragma: /** @jsxImportSource hono/jsx */

Important: Files using JSX must have a .tsx extension. Rename .ts to .tsx or the compiler will fail.

Components

import type { PropsWithChildren } from 'hono/jsx'

const Layout = (props: PropsWithChildren) => (
  <html>
    <head>
      <title>My App</title>
    </head>
    <body>{props.children}</body>
  </html>
)

const UserCard = ({ name }: { name: string }) => (
  <div class="card">
    <h2>{name}</h2>
  </div>
)

app.get('/', (c) => {
  return c.html(
    <Layout>
      <UserCard name="Alice" />
    </Layout>
  )
})

jsxRenderer Middleware

Use jsxRenderer middleware for layouts. See npx hono docs /docs/middleware/builtin/jsx-renderer for details.

Async Components

const UserList = async () => {
  const users = await fetchUsers()
  return (
    <ul>
      {users.map((u) => (
        <li>{u.name}</li>
      ))}
    </ul>
  )
}

Fragments

const Items = () => (
  <>
    <li>Item 1</li>
    <li>Item 2</li>
  </>
)

---

Streaming

import { stream, streamText, streamSSE } from 'hono/streaming'

// Basic stream
app.get('/stream', (c) => {
  return stream(c, async (stream) => {
    stream.onAbort(() => console.log('Aborted'))
    await stream.write(new Uint8Array([0x48, 0x65]))
    await stream.pipe(readableStream)
  })
})

// Text stream
app.get('/stream-text', (c) => {
  return streamText(c, async (stream) => {
    await stream.writeln('Hello')
    await stream.sleep(1000)
    await stream.write('World')
  })
})

// Server-Sent Events
app.get('/sse', (c) => {
  return streamSSE(c, async (stream) => {
    let id = 0
    while (true) {
      await stream.writeSSE({
        data: JSON.stringify({ time: new Date().toISOString() }),
        event: 'time-update',
        id: String(id++)
      })
      await stream.sleep(1000)
    }
  })
})

---

Testing with app.request()

Test endpoints without starting an HTTP server:

// GET
const res = await app.request('/posts')
expect(res.status).toBe(200)
expect(await res.json()).toEqual({ posts: [] })

// POST with JSON
const res = await app.request('/posts', {
  method: 'POST',
  body: JSON.stringify({ title: 'Hello' }),
  headers: { 'Content-Type': 'application/json' }
})

// POST with FormData
const formData = new FormData()
formData.append('name', 'Alice')
const res = await app.request('/users', { method: 'POST', body: formData })

// Using Request object
const req = new Request('http://localhost/api', { method: 'DELETE' })
const res = await app.request(req)

---

Hono Client (RPC)

Type-safe API client using shared types between server and client.

IMPORTANT: Routes MUST be chained for type inference to work. Without chaining, the client cannot infer route types.

// Server: routes MUST be chained to preserve types
const route = app
  .post('/posts', zValidator('json', schema), (c) => {
    return c.json({ ok: true }, 201)
  })
  .get('/posts', (c) => {
    return c.json({ posts: [] })
  })
export type AppType = typeof route

// Client: use hc() with the exported type
import { hc } from 'hono/client'
import type { AppType } from './server'

const client = hc<AppType>('http://localhost:8787/')
const res = await client.posts.$post({ json: { title: 'Hello' } })
const data = await res.json() // fully typed

Type utilities:

import type { InferRequestType, InferResponseType } from 'hono/client'

type ReqType = InferRequestType<typeof client.posts.$post>
type ResType = InferResponseType<typeof client.posts.$post, 200>

---

Helpers

Helpers are utility functions imported from hono/<helper-name>:

import { getConnInfo } from 'hono/conninfo'
import { getCookie, setCookie, deleteCookie } from 'hono/cookie'
import { css, Style } from 'hono/css'
import { createFactory } from 'hono/factory'
import { html, raw } from 'hono/html'
import { stream, streamText, streamSSE } from 'hono/streaming'
import { testClient } from 'hono/testing'

Available helpers: Accepts, Adapter, ConnInfo, Cookie, css, Dev, Factory, html, JWT, Proxy, Route, SSG, Streaming, Testing.

For details, use npx hono docs /docs/helpers/<helper-name>.

Factory

Use createFactory to define Env once and share it across app, middleware, and handlers:

import { createFactory } from 'hono/factory'

const factory = createFactory<Env>()

// Create app (Env type is inherited)
const app = factory.createApp()

// Create middleware (Env type is inherited, no need to pass generics)
const mw = factory.createMiddleware(async (c, next) => {
  await next()
})

// Create handlers separately (preserves type inference)
const handlers = factory.createHandlers(logger(), (c) => c.json({ message: 'Hello' }))
app.get('/api', ...handlers)

---

Best Practices

• Write handlers inline in route definitions for proper type inference of path params.
• Use app.route() to organize large apps by feature, not Rails-style controllers.
• Use createFactory() to share Env type across app, middleware, and handlers.
• Use c.set()/c.get() to pass data between middleware and handlers.
• Chain validators for multiple request parts (param + query + json).
• Export app type for RPC: export type AppType = typeof routes
• Use app.request() for testing — no server startup needed.

Vercel Deployment

On Vercel, just use the default export — no adapter needed:

export default app

For local development without vc dev, you can use the Node.js adapter:

import { serve } from '@hono/node-server'
serve(app)

Keep this in a separate file (e.g., src/lib/local.ts) so it doesn't affect the Vercel deployment.