---
title: Alter headers
description: Example of how to add, change, or delete headers sent in a request or returned in a response.
image: https://developers.cloudflare.com/dev-products-preview.png
---

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# Alter headers

Example of how to add, change, or delete headers sent in a request or returned in a response.

If you want to get started quickly, click on the button below.

[![Deploy to Cloudflare](https://deploy.workers.cloudflare.com/button)](https://deploy.workers.cloudflare.com/?url=https://github.com/cloudflare/docs-examples/tree/main/workers/alter-headers)

This creates a repository in your GitHub account and deploys the application to Cloudflare Workers.

* [  JavaScript ](#tab-panel-11904)
* [  TypeScript ](#tab-panel-11905)
* [  Python ](#tab-panel-11906)
* [  Hono ](#tab-panel-11907)

JavaScript

```
export default {  async fetch(request) {    const response = await fetch("https://example.com");
    // Clone the response so that it's no longer immutable    const newResponse = new Response(response.body, response);
    // Add a custom header with a value    newResponse.headers.append(      "x-workers-hello",      "Hello from Cloudflare Workers",    );
    // Delete headers    newResponse.headers.delete("x-header-to-delete");    newResponse.headers.delete("x-header2-to-delete");
    // Adjust the value for an existing header    newResponse.headers.set("x-header-to-change", "NewValue");
    return newResponse;  },};
```

TypeScript

```
export default {  async fetch(request): Promise<Response> {    const response = await fetch(request);
    // Clone the response so that it's no longer immutable    const newResponse = new Response(response.body, response);
    // Add a custom header with a value    newResponse.headers.append(      "x-workers-hello",      "Hello from Cloudflare Workers",    );
    // Delete headers    newResponse.headers.delete("x-header-to-delete");    newResponse.headers.delete("x-header2-to-delete");
    // Adjust the value for an existing header    newResponse.headers.set("x-header-to-change", "NewValue");
    return newResponse;  },} satisfies ExportedHandler;
```

Python

```
from workers import Response, fetch, WorkerEntrypoint
class Default(WorkerEntrypoint):  async def fetch(self, request):      response = await fetch("https://example.com")
      # Grab the response headers so they can be modified      new_headers = response.headers
      # Add a custom header with a value      new_headers["x-workers-hello"] = "Hello from Cloudflare Workers"
      # Delete headers      if "x-header-to-delete" in new_headers:          del new_headers["x-header-to-delete"]      if "x-header2-to-delete" in new_headers:          del new_headers["x-header2-to-delete"]
      # Adjust the value for an existing header      new_headers["x-header-to-change"] = "NewValue"
      return Response(response.body, headers=new_headers)
```

TypeScript

```
import { Hono } from 'hono';
const app = new Hono();
app.use('*', async (c, next) => {  // Process the request with the next middleware/handler  await next();
  // After the response is generated, we can modify its headers
  // Add a custom header with a value  c.res.headers.append(    "x-workers-hello",    "Hello from Cloudflare Workers with Hono"  );
  // Delete headers  c.res.headers.delete("x-header-to-delete");  c.res.headers.delete("x-header2-to-delete");
  // Adjust the value for an existing header  c.res.headers.set("x-header-to-change", "NewValue");});
app.get('*', async (c) => {  // Fetch content from example.com  const response = await fetch("https://example.com");
  // Return the response body with original headers  // (our middleware will modify the headers before sending)  return new Response(response.body, {    headers: response.headers  });});
export default app;
```

You can also use the [custom-headers-example template ↗](https://github.com/kristianfreeman/custom-headers-example) to deploy this code to your custom domain.

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