Chrome starts testing 'information-reduced user agent strings'

Google announced that it plans to phase out user agent strings in Chrome, but from September 14, 2021, Chrome 95 beta version scheduled to be released on September 23, 2021, Announced that it will start testing 'user agent strings with reduced information'.

User-Agent Reduction origin trial - Chrome Developers
https://developer.chrome.com/blog/user-agent-reduction-origin-trial/

A user agent string is a string that allows the server to identify the operating system, vendor, browser information, etc. when the browser accesses the website. The server sometimes displays a website or provides a service according to the user's environment, but the user agent string is used for this determination. However, in recent years, it has been pointed out that the user agent string can be used as a fingerprint for personal identification. Google plans to abolish cookies in Chrome to improve privacy, but announced in January 2020 that it will phase out user agent strings as well.

Google plans to phase out user agent strings in Chrome - GIGAZINE

by Tati Tata

On September 14, 2021, Google published a new article on Chrome Developers titled ``Reduced User Agent Origin Trial ''. In the article, Google's senior software engineer, Ali Chivkura, and others, first Google the information contained in the user agent string 'browser name and major version' 'desktop or mobile' 'running platform I explained that we are making new efforts to limit it only to '.

They'll also be launching an information-reduced user-agent origin trial, which will allow websites to opt- in to receiving the reduced user-agent beginning with the Chrome 95 beta, which is scheduled to be released on September 23. announced that it will This allows websites to test on reduced user agents before a stable version is released.

When a reduced user agent is applied, it affects the information that can be obtained with:

・'User-Agent' in the HTTP request header
・Javascript getter 'navigator.userAgent'
・Javascript getter 'navigator.platform'
・Javascript getter 'navigator.appVersion'

Here's how to join the Origin Trial:

◆1: Access the origin trial registration page and register to get a token for your website.
◆2: Update the HTTP response header.
1. Add 'Origin-Trial: Origin-Trial Token' to the HTTP response header, including the 'Origin-Trial Token' you got when you registered.
2. Add 'Accept-CH: Sec-CH-UA-Reduced' to the HTTP response header.
3. Setting 'Accept-CH' will cause the reduced user-agent string to be sent only on subsequent requests to the origin. To resend the reduced user-agent string in the initial navigation request, add 'Critical-CH: Sec-CH-UA-Reduced' to the HTTP response header in addition to the 'Accept-CH' and 'Origin-Trial' headers. add to
Four. To allow third-party subresource requests to receive a reduced user-agent string, add a 'Permissions-Policy' with the third-party domain.
◆3: Load the website with Chrome M95 or later and receive the reduced user agent string.
◆ 4: Issues and feedback to GitHub .
◆ 5: A simple demonstration and source code of the origin trial can be confirmed from the following.

User-Agent Reduction Origin Trial Demo Site
https://uar-ot.glitch.me/

Note that if you want to get more information than is shared by the reduced user agent, you should migrate to the User-Agent Client Hints API .