ACE (WinAce Compressed File)
The ACE Archive file format
The ACE file extension is assigned to archive files that have been compressed using WinAce. It's one of the formats supported by WinAce and can be decompressed by few other compression programs as well.
Technical details of ACE files
ACE archives use a proprietary compression algorithm. The specifications of this algorithm allow for fast compression speed and a very high ratio of compression as well.