there's also base91, with an efficiency of 6.5 bits of data per printable character, compared to 6.4 with ascii85, 6.0 with base64

There's probably a base(bigger number) with Unicode chars today

base65536, and look who the author is :-D

https://github.com/qntm/base65536

Who is the author?

https://www.qntm.org https://news.ycombinator.com/from?site=qntm.org

Base65536? https://github.com/qntm/base65536

But you need to make sure to use utf-16 or utf-32 instead of utf-8, or you may be worse off.

Those get mangled by text editors that don't support them.

While a couple of people suggested Base65536, that encoding isn't particularly compact, and it can't be as elegant as 65536 would suggest because it has to dodge special cases in unicode.

It's almost always the case that either Base32768 is denser, or encodings with 2^17 or 2^20 characters are denser.