No compression format is supported by literally all operating systems. Some OSes don't even have a disk I/O or network I/O.
Having said that, use .zip
as that's natively supported by Windows, it's the most popular format, and it's the core of several other file formats including Open Document Format and Java Archive (jar
). All operating systems that are able to run Java are technically able to unpack zip files. I also assume that almost all modern operating systems have the support to unpack .zip files built in.
If you want to support ancient Unix machines as well, offer .tar.gz
beside .zip
. Even then, said ancient Unix machines should be able to unpack .zip
as well.