Sec-CH-UA-Bitness Header

Table of Content

  • Syntax
  • Directives
  • Examples
  • Browser Compatibility
  • How to modify Sec-CH-UA-Bitness header The Sec-CH-UA-Bitness header is an important HTTP request header which is part of the User-Agent Client Hints API, pertaining to modern web development standards. It gives the server information about the bitness of the user's browser, that is, whether the client's browser is a 32-bit or 64-bit version. This information could be useful in serving the appropriate version of scripts or executables to the client, enhancing the browsing performance and security.


Sec-CH-UA-Bitness: <bitness>

Here <bitness> is the bitness value of the client's browser.


The Sec-CH-UA-Bitness header accepts one directive being the bitness value, which can be either '64' or '32'.


A request header with Sec-CH-UA-Bitness might look something like this:

GET /page.html HTTP/1.1
Sec-CH-UA-Bitness: 64

The above header tells the server that it is a 64-bit browser making the request.

Browser Compatibility

Browser Compatibility
Chrome Supported
Firefox Not Supported
Safari Not Supported
Opera Supported
Edge Supported

How to modify Sec-CH-UA-Bitness header

ModHeader is a powerful Chrome extension that allows you to modify HTTP request headers directly from your browser. By altering the Sec-CH-UA-Bitness header, you can effectively mimic the behavior of different browsers.

To modify the Sec-CH-UA-Bitness header in ModHeader:

  1. Install and open the ModHeader extension on your Chrome browser.
  2. On the ModHeader interface, click 'Request headers'.
  3. In the 'Name' input field, type Sec-CH-UA-Bitness.
  4. In the 'Value' input field, type '64' or '32', depending on your needs.

By faking the Sec-CH-UA-Bitness header, you can potentially debug platform dependent issues, or verify your server's handling of different bitness. However, please note such usage should typically be limited to development environments, and you should respect the privacy regulations when dealing with real users.