---
title: WebSockets
description: Miniflare will always upgrade Web Socket connections. The Worker must respond
with a status 101 Switching Protocols response including a webSocket. For
example, the Worker below implements an echo WebSocket server:
image: https://edgetunnel-b2h.pages.dev/dev-products-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://edgetunnel-b2h.pages.dev/workers/llms.txt  
> Use this file to discover all available pages before exploring further. 

[Skip to content](#%5Ftop) 

# WebSockets

* [WebSockets Reference](https://edgetunnel-b2h.pages.dev/workers/runtime-apis/websockets)
* [Using WebSockets](https://edgetunnel-b2h.pages.dev/workers/examples/websockets/)

## Server

Miniflare will always upgrade Web Socket connections. The Worker must respond with a status `101 Switching Protocols` response including a `webSocket`. For example, the Worker below implements an echo WebSocket server:

**JavaScript**

```js
export default {
  fetch(request) {
    const [client, server] = Object.values(new WebSocketPair());


    server.accept();
    server.addEventListener("message", (event) => {
      server.send(event.data);
    });


    return new Response(null, {
      status: 101,
      webSocket: client,
    });
  },
};
```

When using `dispatchFetch`, you are responsible for handling WebSockets by using the `webSocket` property on `Response`. As an example, if the above worker script was stored in `echo.mjs`:

**JavaScript**

```js
import { Miniflare } from "miniflare";


const mf = new Miniflare({
  modules: true,
  scriptPath: "echo.mjs",
});


const res = await mf.dispatchFetch("https://example.com", {
  headers: {
    Upgrade: "websocket",
  },
});
const webSocket = res.webSocket;
webSocket.accept();
webSocket.addEventListener("message", (event) => {
  console.log(event.data);
});


webSocket.send("Hello!"); // Above listener logs "Hello!"
```

```json
{"@context":"https://schema.org","@type":"TechArticle","@id":"https://edgetunnel-b2h.pages.dev/workers/testing/miniflare/core/web-sockets/#page","headline":"WebSockets · Cloudflare Workers docs","description":"Miniflare will always upgrade Web Socket connections. The Worker must respond\nwith a status 101 Switching Protocols response including a webSocket. For\nexample, the Worker below implements an echo WebSocket server:","url":"https://edgetunnel-b2h.pages.dev/workers/testing/miniflare/core/web-sockets/","inLanguage":"en","image":"https://edgetunnel-b2h.pages.dev/dev-products-preview.png","dateModified":"2026-01-28","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://edgetunnel-b2h.pages.dev/#website","name":"Cloudflare Docs","url":"https://edgetunnel-b2h.pages.dev/"}}
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/testing/","name":"Testing"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/testing/miniflare/","name":"Miniflare"}},{"@type":"ListItem","position":5,"item":{"@id":"/workers/testing/miniflare/core/","name":"Core"}},{"@type":"ListItem","position":6,"item":{"@id":"/workers/testing/miniflare/core/web-sockets/","name":"WebSockets"}}]}
```