See SourceForge download page for downloads.

Unofficial Chinese translation can be found here.
Unofficial Japanese translation can be found here.

Change log (Windows GUI):

1.2.1.24
[*] - Internet Explorer 7 compatibility update

1.2.0.23 fixed
[+] - statistics show size of archive which won't be exceeded
[+] - KGB Archiver shows summary window on taskbar now
[*] - other cosmetic changes

1.2.0.23
[+] - added wizard
[+] - added Turkish, Lithuanian, Swedish, Spanish (Spain), Estonian, German translations
[+] - added possibility to remove statistics window after compression/decompression
[+] - added ask for cancel compression/decompression process
[+] - new window for overwriting files & added overwrite ask while decompressing zip archives (my mistake from previous version)
[+] - added recent archives & dirs list
[+] - added speed column to memory usage table
[+] - added icons on files list
[+] - keep settings between instalations
[*] - fixed: compress file to the same archive name (it creates broken archive)
[*] - fixed: tray icon removal after compression/decompression
[*] - block compression of files bigger than 4GB (it crashed archiver)
[*] - changed read buffer size from 64kb to 32kb (smaller memory usage ;)
[*] - updated some translations
[*] - some languages have native names on language list

1.1.5.22
[*] - security update: directory traversal vulnerability while decompressing archive, thanks to Joxean Koret

1.1.4.21
[+] - KGB Archiver blocks compression/decompression when there is not enough free memory
[+] - added check if file exists and ask for overwrite it when decompressing
[+] - added possibility to manual change of language
[+] - added Italian, Hungarian, Dutch, Czech translation
[*] - fixed: possibility to add duplicated files to archive, when compressing whole folders
[*] - minor changes

1.1.3.20
[*] - security bug fixed (info about it is confidential due to safety of older version users)

1.1.2.19
[+] - added translations: Portuguese (Brazil), Spanish (Chile), French, Romanian (KGB Archiver automatically choose correct language depending on windows language version and country code)
[+] - added support for encrypted SFX KGB archives (older SFX archives should be opened without problems)
[+] - added minimize button to main windows of compressing and decompressing ;)
[+] - added 'Extract here' option in windows explorer context menu
[*] - fixed: priority indicator returns to normal after minimize to tray and restore
[*] - minor changes

1.1.1.18
[+] - added compression in background mode
[+] - added ability to add files by drag'n'drop method
[+] - added archive statistics field after opening archive
[+] - added calculation of units if it's bigger than 1024 (B -> KB -> MB -> GB)
[*] - added elapsed time information after compression/decompression
[*] - fixed error, which place full path without drive letter in ZIP archives, when compressing with 'Keep full path' option
[*] - fixed errors in English translation
[*] - minor changes

1.1.0.17
[+] - added ZIP support
[*] - improved statistics
[*] - fixed error, which could block decompression of KGB archives on some systems
[*] - completed English translation
[*] - new icons
[*] - minor changes

1.0.4.16
[*] - fixed statistics (wrong progress indicator, while creating bigger archive than 40,96MB & wrong remaining time when it's bigger than 10h)
[*] - added support for archives up to 4GB (instead of 2GB)
[*] - faster compression (about 2,5%)

1.0.3.15
[+] - KGB Archiver saves settings before exit
[+] - added auto-update module
[+] - added dialog during decryption of archive (which can take few seconds)
[*] - improved statistics

1.0.2.14
[+] - progress is shown on the title bar during compression
[*] - English translation repaired
[*] - improved performance of encryption/decryption (about 5%)
[-] - removed Chinese and Russian translations due to compatibility issues

Change log (POSIX):

1.0 beta 4
[*] - security update: directory traversal vulnerability while decompressing archive, thanks to Joxean Koret

1.0 beta 3
[+] - added English translation
[*] - minor changes

Rest of change log is here (polish version only).