They would be a lot more useful if they were more straighforward and honest.

Just give me "Chrome 68" instead of "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36"

firefox has a sane user agent. mine is:

>Mozilla/5.0 (X11; Linux x86_64; rv:65.0) Gecko/20100101 Firefox/65.0

edit: sorry, accidentally submitted early

So what. Removing one of the largest sources entropy available for fingerprinting users is important. We shouldn't maintain the terrible long-term effects[1] of tracking everything just to help you have an easier time debugging.

[1] http://nymag.com/intelligencer/2019/02/shoshana-zuboff-q-and...

Does it really provide that much entropy? Maybe back in the days when browsers didn’t auto-update, but intuitively it should only provide about four bits at most (os: Android iOS macOS windows, browser: chrome safari edge ie ff) except for a few rare users who don’t stay up to date or choose a weird browser (and those folks probably are a little confused about how privacy works).

ohhhhh you betcha.

https://amiunique.org/

i ran this on my work laptop (windows 10 / firefox - mostly default settings). the "details" tab shows a full breakdown of each fingerprinting component with a "similarity ratio" (percentage of fingerprints that share the same value).

every entry is 20% or greater, most of them around 50% except for timezone (4%), canvas (1%), and user agent (0.12%).

so, yeah, user agents are still the largest source of entropy by a wide margin for fingerprinting scripts.

I suspect this is just stale data. I can’t think why the most recent version of a browser would put me at one in a thousand.

There are better solutions available than hanging functionality on unreliable vestigial bits and pieces that shouldn't be there anyway which, because others abuse the functionality, you can't trust to be correct for debugging purposes.

99% of the traffic has the correct user-agent which is useful in tracking down issues that are browser specific. The other 1% will just get ignored as noise. And it's not like we can't tell what type of browser they are using with browser specific objects that we can pull from javascript. We just can't infer the version of the browser which is critical for debugging issues.

I use a randomized user agent and every once in a while get rejected by a site that has decided my browser can't be supported. Usually when I'm on some Safari version. I doubt much effort is being done to identify fake user agents since there are better fruit to pick in the fingerprinting game.

That might be true, although you don't list the solutions, but it doesn't refute my point in any case.

Per https://webkit.org/blog/8042/release-notes-for-safari-techno... the user agent is frozen in webkit now.

You're writing your websites wrong.

I've had to debug around a short-lived bug in the Firefox rendering engine that only showed up in the FF rendering engine before. The site itself? Standards-compliant; there was flexibility in the standard (ironically, for flexboxes ;) ) about performance constraints and our site just fell down Gecko's slowness tree and hit every branch on the way.

Given the engines are allowed to vary, this experience is inevitable from time to time. The user-agent is really valuable in helping us figure out when that's what we're seeing.

If there’s a way to write them without the occasional browser-specific bug, I’d sure like to know what it is.