You're talking about WURFL and Luca Passani. I recall working with it for a project 15 years ago.

https://en.wikipedia.org/wiki/WURFL

Same here... back in 2011 or so. We needed something much more performant than WURFL. My efforts eventually became a feature/product at Akamai known as "Edge Device Characterization" (EDC) using algorithms not dissimilar to how LLMs are trained today.

I can't speak to how good the actual product is today (or even when it launched, but that's a whole 'nother story), but during development it was capable of processing 100K RPS in a footprint of ~30MB RAM with ~98% accuracy compared to WURFL as a baseline.

Wow, I remember WURFL! I used this at my second-ever job, back when mobile was still taking off, and we were trying to create some sort of mobile-server-plugin-thing for a big Java CMS monstrosity thing, as well as running NYC Restaurant Week's mobile site.

Those were not the good ol' days.

BTW: It looks like WURFL is still a thing. He seems to have made a business of it[0].

The key to WURFL was a massive XML file. That was constantly updated with the latest gizmos, and whatnot.

[0] https://www.scientiamobile.com

Yup. That's it.