Free compression software for mac

The Lossless Compression Plugin for REALbasic v3.0 or newer uses lossless compression algorithms (LZRW3-A, LZSS and zlib v1.1.4) to compress binary or text data.

The Lossless Compression Plugin provides additionally routines for the calculation of CRC32 and Adler32 checksums.

Archive a lot of files? Do you wish you had access to more file compression methods than Apple offers from the Finder but without the price of StuffIt? Enter Compress. Compress is a simple way to decrease file sizes. Not only that, but its free!
Compress gives you support for .tar, .gz, .bz2, and even .zip compression. Now you can send files in any of the geeky compression methods that you want. Not only that, but Compress also decompresses for you.
It can handle files that have been compressed many times. Want to tar then gzip a folder? Compress will let you do that. Got a file called "folder.gz.tar"? Compress will extract those files without breaking a stride.
Using Compress couldnt be easier. Simply launch the application and drag a file or a folder onto the main window. Compress handles the rest from there. If you drag a compressed file onto the window, Compress will decompress it. It can do multi-step compression and decompression without any extra hassles.
Enhancements:
- Now a universal binary
- Adds dmg compression
- Improved tar compression
- Improved gzip compression
- Improved bz2 compression
- Contains latest to date p7zip (7za) command line application.

swfShrink is a Java-based freeware that enables to (re-)compress images of a Flash movie to reduce its file size.
Main features:
- manual selection of images to (re-)compress (only 32 bit lossless compressed images)
- manual tuning of the JPG quality for each recompressed image
- direct visualisation of compression loss on each image
- direct calculation of the compression rate for each JPG quality.

GraphicsImporter is a small scripting addition which enables you to change the status, format, size, resolution, color depth, compression rate of any image.

In addition with GraphicsImporter you can also scale and rotate images.

Completly freeware.

Shorten 1.1a3 brings an advanced and complete utility developed by Tony Robinson and SoftSound Limited to convert audio files to and from a compressed format. Compression of about 50% is typical. MP3 compression is usually much greater, but unlike MP3 files, shortened files result in no loss of fidelity. Shorten for Macintosh has a graphical user interface and also contains the md5sum checksum utility which can be used to verify file integrity.