7-Zip

7-Zip
Open-source compression software.

Supports a variety of compression formats, such as ZIP, GZIP, BZIP2 and TAR, RAR, CAB, ISO, ARJ, LZH, CHM, Z, CPIO, RPM, DEB and NSIS.

As well as these, it also has its own format, 7z, which has a high compression ratio.