We just released a new freeware product called SB-MD5. SB-MD5 Checksum Calculator is a tool to calculate and compare the MD5 checksum of files. The MD5 checksum is used worldwide for checking the integrity of files. The MD5 checksum has been around for over 10 years. It was designed by professor Ronald L Rivest in 1991. The MD5 algorithm has been used by many security applications and integrity control applications since it was published as an internet standard (RFC-1321) in 1992. The MD5 checksum is like a fingerprint of a file.