storeBackup is a backup utility that stores files on other disks. It's able to compress data, and recognize copying and moving of files and directories (deduplication), and unifies the advantages of traditional full and incremental backups. It can handle big image files with block-wise changes efficiently. Depending on its contents, every file is stored only once on disk. Tools for analyzing backup data and restoring are provided. Once archived, files are accessible by mounting file systems (locally, or via Samba or NFS). It is easy to install and configure. Additional features are backup consistency checking, offline backups, and replication of backups.
pngcrush is an excellent batch-mode compression utility for PNG images. Depending on the application that created the original PNGs, it can improve the file size anywhere from a few percent to 40% or more (completely losslessly). The utility also allows specified PNG chunks (e.g. text comments) to be inserted or deleted, and it can fix incorrect gamma info written by Photoshop 5.0 as well as the erroneous iCCP chunk written by Photoshop 5.5.
The RAZip bitstream format was designed to provide a faster random access to compressed data than what is currently possible using the GZIP format. Its major features include fast random access to compressed data, freedom from patents, single-pass coding/decoding using a bounded amount of intermediate storage, the ability to choose from one of many algorithms for compression, encryption, or error correction, and comprehensive support for Unix file metadata, Macintosh file metadata, and arbitrary file metadata.
Shoelacer attempts to generate a pair of small C functions that compress or decompress a set of data (primarily short strings) presented to it, and possibly other data of that kind. The data it is given may consist of entries of just a few bytes or longer. Its goal is to be reasonably fast with a tiny memory overhead. Compression performance is not so much the goal, although it certainly isn't ignored.
The lzlib compression library provides in-memory LZMA compression and decompression functions, including integrity checking of the decompressed data. The compressed data format used by the library is the lzip format. The lzip file format is designed for long-term data archiving. It is clean, provides very safe 4-factor integrity checking, and is backed by the recovery capabilities of lziprecover.
Lbzip2 is a parallel, SMP-based, bzip2-compatible compression utility, with a commandline resembling that of the original bzip2. It is usable both on its own and as a filter passed to GNU tar with the "--use-compress-program" option. It uses Gnulib, and its building and testing process is managed by the GNU build system. Starting with release 2.0, lbzip2 is independent of libbz2 and features yambi, an independent BWT compression stack with improved speed and robustness.