If you downloaded a file that came in the unknown archive format, the best way is to first convert it into a known archive format and then extract the contents. Many archive tools such as WinRar and 7Zip support conversions into other archive formats, but they lack support of many other popular formats.
ArcConvert is a free portable tool for Windows that allows you to convert many different types of archives to known formats. It can convert the following archives,
7-ZIP, LZH, CAB, ZIP, ARJ, ACE, RAR, TAR, TGZ, GZ, Z, BZ2, YZ1, YZ2, GCA, BEL, RPM, DEB, BH, Noa32, HKI, PAQAR, SQX, HA, ZOO, UHARC, LFB, ZLIB, UCL, IMP, RS, SPL, APK, Arc, DZ, MSI, ALZ, PMA, PAQ7, CHM, UDA, PAQ8, Cryptonite, ISO, LZOP, BMA, ZIP AES (128/192/256), Nanozip Alpha, XZ
into the following ones,
ZIP, 7-ZIP, CAB, LHA, TAR, TGZ, BZ2, YZ1, BGA, RAR, ACE, NOA32, HKI, PAQAR, UHARC, YZ2, DZ, HA, XZ.Read More