Those who do not know judy1 are doomed to reinvent it.
the Judy project seems inactive to me:
https://sourceforge.net/p/judy/bugs/
this short HN thread resonates with the intuition of jude1 being stalled, it's last optimistic comment points to an orphaned comment in the big list above
On the surface it's just a very optimized 256-ary radix trie. I think it would take some software archeology to determine if there was more to it than that and if it's assumptions still hold on todays processors.
It's not written in an highly unstable language. The safety of every bridge you drive over was probably partially validated using fortran numerical code from the 1980s.
said fortran code happily gets minor and major updates
plus it may not benefit from contemporary advances in silicon architecture, etc.
Today it'd make much more sense to implement ART, which is dramatically simpler.
Jokes aside, it took me quite a bit of trial and error to figure out that you are (probably) referring to Adaptive Radix Trees. Because "art tree" doesn't exactly give useful results.