> The fact that "encode.su" uses the world's most notorious domain extension doesn't inspire confidence, to put it mildly.

Encode.su (formerly encode.ru) is indeed the most known forum dedicated for data compression in general. So much that many if not most notable data compression projects posted to HN are often first advertised to that forum first (for example, Zstandard [1]).

[1] https://encode.su/threads/2119-Zstandard