PackDir is an extremely fast file archiver. It can take a set of files and put them all together in a single archive file. It can also perform the reverse process, i.e. it can exactly recreate the original set of files from the archive file. To make archive files as small as possible, PackDir can perform lossless compression on file data, which reduces the archive's size typically to about 50% (or even much less, depending on the nature of the file data).