---
title: Format of HTTP request header names and values · Cloudflare Rules docs
description: "The name of the HTTP request header you want to set or remove can
  only contain:"
lastUpdated: 2025-08-20T20:59:04.000Z
chatbotDeprioritize: false
source_url:
  html: https://developers.cloudflare.com/rules/transform/request-header-modification/reference/header-format/
  md: https://developers.cloudflare.com/rules/transform/request-header-modification/reference/header-format/index.md
---

The **name** of the HTTP request header you want to set or remove can only contain:

* Alphanumeric characters: `a`-`z`, `A`-`Z`, and `0`-`9`
* The following special characters: `-` and `_`

The **value** of the HTTP request header you want to set can only contain:

* Alphanumeric characters: `a`-`z`, `A`-`Z`, and `0`-`9`
* The following special characters: ``_ :;.,\/"'?!(){}[]@<>=-+*#$&`|~^%``
