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Alter headers

Example of how to add, change, or delete headers sent in a request or returned in a response.
 Run Worker
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;
},
};
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;
from js import Response, fetch
async def on_fetch(request):
response = await fetch("https://example.com")
# Clone the response so that it's no longer immutable
new_response = Response.new(response.body, response)
# Add a custom header with a value
new_response.headers.append(
"x-workers-hello",
"Hello from Cloudflare Workers"
)
# Delete headers
new_response.headers.delete("x-header-to-delete")
new_response.headers.delete("x-header2-to-delete")
# Adjust the value for an existing header
new_response.headers.set("x-header-to-change", "NewValue")
return new_response

You can also use the custom-headers-example template to deploy this code to your custom domain.