The problem with User-Agent strings

If you regularly check your website’s analytics, you may have noticed something weird in the past year or two. None of your visitors use Windows 11, and nobody upgraded their computer past macOS 10.15 Catalina. That can’t be right. So what is going on?

Your analytics packages recognise the browser by looking at the User-Agent string. Every request the browser makes includes that string, which contains a lot of information about your computer, the operating system, and your browser. 

Over the last few years, that information has suddenly become less reliable, often giving us fake information. Why is that, and what can we do? And more importantly, do we even need to know these details in the age of evergreen browsers? 

To answer those questions, we need to examine the history of the User-Agent string. It is a somewhat complicated story, so I decided to split it into six parts: