I did quick internet search and only app mentioned by people that is able to achieve such compression rate is KGB Archiver[1]. And according to its wikipedia pa

I did quick internet search and only app mentioned by people that is able to achieve such compression rate is KGB Archiver[1]. And according to its wikipedia page it uses PAQ[2]. [1] https://en.wikipedia.org/wiki/KGB_Archiver https://en.wikipedia.org/wiki/KGB_Archiver [2] https://en.wikipedia.org/wiki/PAQ6 https://en.wikipedia.org/wiki/PAQ6