---
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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### Tags

[ Headers ](https://developers.cloudflare.com/search/?tags=Headers)[ Middleware ](https://developers.cloudflare.com/search/?tags=Middleware)[ JavaScript ](https://developers.cloudflare.com/search/?tags=JavaScript)[ TypeScript ](https://developers.cloudflare.com/search/?tags=TypeScript)[ Python ](https://developers.cloudflare.com/search/?tags=Python) 

# Alter headers

**Last reviewed:**  over 5 years ago 

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-9206)
* [  TypeScript ](#tab-panel-9207)
* [  Python ](#tab-panel-9208)
* [  Hono ](#tab-panel-9209)

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.

```json
{"@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/examples/","name":"Examples"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/examples/alter-headers/","name":"Alter headers"}}]}
```