---
title: Alter headers
description: Example of how to add, change, or delete headers sent in a request or returned in a response.
image: https://edgetunnel-b2h.pages.dev/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-12443)
* [  TypeScript ](#tab-panel-12444)
* [  Python ](#tab-panel-12445)
* [  Hono ](#tab-panel-12446)

**JavaScript**

```js
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**

```ts
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**

```py
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**

```ts
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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```