---
title: WebSockets now automatically reply to Close frames
description: The Workers runtime now automatically sends a reciprocal Close frame when it receives a Close frame from the peer, matching standard WebSocket behavior.
image: https://developers.cloudflare.com/changelog-preview.png
---

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## WebSockets now automatically reply to Close frames

Apr 07, 2026 

[ Workers ](https://developers.cloudflare.com/workers/) 

The Workers runtime now automatically sends a reciprocal Close frame when it receives a Close frame from the peer. The `readyState` transitions to `CLOSED` before the `close` event fires. This matches the [WebSocket specification ↗](https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/close%5Fevent) and standard browser behavior.

This change is enabled by default for Workers using compatibility dates on or after `2026-04-07` (via the [web\_socket\_auto\_reply\_to\_close](https://developers.cloudflare.com/workers/configuration/compatibility-flags/#websocket-auto-reply-to-close) compatibility flag). Existing code that manually calls `close()` inside the `close` event handler will continue to work — the call is silently ignored when the WebSocket is already closed.

JavaScript

```
const [client, server] = Object.values(new WebSocketPair());server.accept();
server.addEventListener("close", (event) => {  // readyState is already CLOSED — no need to call server.close().  console.log(server.readyState); // WebSocket.CLOSED  console.log(event.code); // 1000  console.log(event.wasClean); // true});
```

#### Half-open mode for WebSocket proxying

The automatic close behavior can interfere with WebSocket proxying, where a Worker sits between a client and a backend and needs to coordinate the close on both sides independently. To support this use case, pass `{ allowHalfOpen: true }` to `accept()`:

JavaScript

```
const [client, server] = Object.values(new WebSocketPair());
server.accept({ allowHalfOpen: true });
server.addEventListener("close", (event) => {  // readyState is still CLOSING here, giving you time  // to coordinate the close on the other side.  console.log(server.readyState); // WebSocket.CLOSING
  // Manually close when ready.  server.close(event.code, "done");});
```

For more information, refer to [WebSockets Close behavior](https://developers.cloudflare.com/workers/runtime-apis/websockets/#close-behavior).

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