MakePAK is a command-line tool for creating Quake .PAK files. It is supposed to be paired with PhysicsFS, which can read Quake .PAK archives. It follows the GNU standards, providing a portable, consistent, and complete utility.
Cyphertite is a tar-like secure remote archiver. It deduplicates, compresses, and encrypts data prior to transmission, providing total privacy while reducing unnecessary wire traffic. It seamlessly supports IPv6 and IPv4 on a variety of platforms.
btar is a tar-compatible archiver which allows arbitrary compression and ciphering, redundancy, differential backup, indexed extraction, multicore compression, input and output serialisation, and tolerance to partial archive errors.
innoextract is a tool that allows you to extract the contents of Inno Setup installers on non-Windows systems. It does so without running the actual installer using Wine.