> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/honojs/hono/llms.txt
> Use this file to discover all available pages before exploring further.

# Cloudflare Workers

> API reference for the Cloudflare Workers adapter

The Cloudflare Workers adapter provides utilities for running Hono applications on Cloudflare Workers.

## Import

```ts theme={null}
import { serveStatic, upgradeWebSocket, getConnInfo } from 'hono/cloudflare-workers'
```

## Functions

### serveStatic()

<Warning>
  `serveStatic` in the Cloudflare Workers adapter is deprecated. You can serve static files directly using [Cloudflare Static Assets](https://developers.cloudflare.com/workers/static-assets/).

  Cloudflare Static Assets is currently in open beta. If this doesn't work for you, please consider using Cloudflare Pages. You can start to create the Cloudflare Pages application with the `npm create hono@latest` command.
</Warning>

Middleware for serving static files from Cloudflare Workers KV.

```ts theme={null}
function serveStatic<E extends Env = Env>(
  options: ServeStaticOptions<E>
): MiddlewareHandler
```

#### Parameters

* `options.manifest` - `object | string` - Asset manifest for KV
* `options.namespace` - `KVNamespace` (optional) - KV namespace to use
* Additional options from base `ServeStaticOptions`

#### Example

```ts theme={null}
import { Hono } from 'hono'
import { serveStatic } from 'hono/cloudflare-workers'
import manifest from '__STATIC_CONTENT_MANIFEST'

const app = new Hono()

app.get('/static/*', serveStatic({ 
  manifest,
  namespace: env.__STATIC_CONTENT 
}))

export default app
```

### upgradeWebSocket()

Helper function to upgrade HTTP connections to WebSocket connections in Cloudflare Workers.

```ts theme={null}
function upgradeWebSocket<T>(
  createEvents: (c: Context) => WSEvents
): MiddlewareHandler
```

#### Parameters

* `createEvents` - Function that receives context and returns WebSocket event handlers:
  * `onMessage` - Called when a message is received
  * `onClose` - Called when the connection closes
  * `onError` - Called on error

<Note>
  Cloudflare Workers doesn't support the `onOpen` event. The connection is established after the handler returns.
</Note>

#### Example

```ts theme={null}
import { Hono } from 'hono'
import { upgradeWebSocket } from 'hono/cloudflare-workers'

const app = new Hono()

app.get(
  '/ws',
  upgradeWebSocket((c) => {
    return {
      onMessage(event, ws) {
        console.log(`Message from client: ${event.data}`)
        ws.send('Hello from server!')
      },
      onClose: () => {
        console.log('Connection closed')
      },
      onError(evt) {
        console.log('WebSocket error:', evt)
      },
    }
  })
)

export default app
```

### getConnInfo()

Extracts connection information from the Cloudflare Workers request.

```ts theme={null}
function getConnInfo(c: Context): ConnInfo
```

#### Returns

```ts theme={null}
interface ConnInfo {
  remote: {
    address?: string // Client IP from cf-connecting-ip header
  }
}
```

#### Example

```ts theme={null}
import { Hono } from 'hono'
import { getConnInfo } from 'hono/cloudflare-workers'

const app = new Hono()

app.get('/', (c) => {
  const info = getConnInfo(c)
  return c.text(`Your IP: ${info.remote.address}`)
})

export default app
```

## Platform-Specific Notes

* Cloudflare Workers uses the `cf-connecting-ip` header to identify the client's IP address
* WebSocket connections require special handling with `WebSocketPair`
* The `onOpen` event is not available for WebSockets in Cloudflare Workers
* Static file serving is deprecated in favor of Cloudflare Static Assets or Cloudflare Pages

## See Also

* [Cloudflare Workers Documentation](https://developers.cloudflare.com/workers/)
* [Cloudflare Static Assets](https://developers.cloudflare.com/workers/static-assets/)
* [WebSocket API in Workers](https://developers.cloudflare.com/workers/runtime-apis/websockets/)