---
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: 2025-04-15T11:19:33.000Z
source_url:
  html: https://77261bbd.preview.developers.cloudflare.com/rules/transform/request-header-modification/reference/header-format/index.md
  md: https://77261bbd.preview.developers.cloudflare.com/rules/transform/request-header-modification/reference/header-format/
---

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: ``_ :;.,\/"'?!(){}[]@<>=-+*#$&`|~^%``
