Hono

Hono Skill

Build Hono web applications. This skill provides inline API knowledge for AI. Use Hono CLI to inspect and test the app.

Latest Documentation

For details beyond this inline reference, fetch the latest documentation from https://hono.dev. Get the index of doc pages from https://hono.dev/llms.txt, then fetch a page with the Accept: text/markdown header to receive it as Markdown:

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curl -H "Accept: text/markdown" https://hono.dev/docs/helpers/cookie

Hono CLI

Use Hono CLI to inspect and test the app. Install it in the project, then let the CLI explain itself:

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npm install -D @hono/cli@next
npx hono agent-context

Follow the output. It explains every command (routes, request, batch, snapshot, benchmark, optimize, ssg), the JSON output contract, and the workflow.

Notes:

• hono request sends a request with app.request() — no server needed. Do not pass credentials directly in CLI arguments; use environment variables for sensitive values.

• For Cloudflare Workers bindings (KV, D1, R2, etc.), use hono request /path --runtime workerd. It starts the app with the wrangler config of the project, so the local bindings (c.env) are real. wrangler must be installed in the project.

• For several requests, or a flow that keeps state (POST, then use the returned id), run them in one hono batch - call. One JSON object per line; save a value and use it as {{id}} in later steps. The steps share one app instance. Declare the expected status/body per step with expect (body is a deep partial match) and iterate until the summary shows "failed": 0:

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  npx hono batch - <<'EOF'
  {"method":"POST","path":"/users","body":{"name":"Alice"},"save":{"id":".id"},"expect":{"status":201}}
  {"path":"/users/{{id}}","expect":{"status":200,"body":{"name":"Alice"}}}
  EOF
  

• Before changing existing routes, capture the current behavior: npx hono snapshot prints it as batch JSONL lines (real responses become the expect). Keep the lines, make the change, then rerun them with npx hono batch - until "failed": 0.

• On a large API, use npx hono snapshot --status-only and npx hono batch - --compact — same loop, much smaller output. A failed step carries diff: fix what it names.

Hono API Reference

App Constructor

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import { Hono } from 'hono'

const app = new Hono()

// With TypeScript generics
type Env = {
  Bindings: { DATABASE: D1Database; KV: KVNamespace }
  Variables: { user: User }
}
const app = new Hono<Env>()

Routing Methods

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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

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// 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

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// 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

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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

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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

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

Variables (request-scoped data)

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

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

Environment (Cloudflare Workers)

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const value = await c.env.KV.get('key')
const db = c.env.DATABASE
c.executionCtx.waitUntil(promise)

Renderer

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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)

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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

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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 { jwk } from 'hono/jwk'
import { csrf } from 'hono/csrf'
import { ipRestriction } from 'hono/ip-restriction'
import { bodyLimit } from 'hono/body-limit'
import { timeout } from 'hono/timeout'
import { requestId } from 'hono/request-id'
import { methodOverride } from 'hono/method-override'
import { methodNotAllowed } from 'hono/method-not-allowed'
import { languageDetector } from 'hono/language'
import { some, every, except } from 'hono/combine'
import { contextStorage, getContext } from 'hono/context-storage'
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

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// 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:

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

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

Validation

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

Zod Validator

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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

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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:

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{
  "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

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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. For details, see https://hono.dev/docs/middleware/builtin/jsx-renderer

Async Components

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

Fragments

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

Streaming

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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:

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// 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 })

// With mock env (Cloudflare Workers bindings)
const res = await app.request('/api/data', {}, { KV: mockKV, DATABASE: mockDB })

// 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.

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// 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:

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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>:

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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'
import { upgradeWebSocket } from 'hono/cloudflare-workers' // or other adapter

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

For details, see https://hono.dev/docs/helpers/<helper-name> (fetch with Accept: text/markdown).

Factory

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

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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.

Adapters

Hono runs on multiple runtimes. The default export works for Cloudflare Workers, Deno, and Bun. For Node.js, use the Node adapter:

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// Cloudflare Workers / Deno / Bun
export default app

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