FastSum is build upon the well proven MD5 checksum algorithm which is used worldwide for checking integrity of the files, and been used for this purpose for at least the last 10 years. FastSum provides you with three interfaces from the console application for technician professionals to modern graphical application for any-level users.

What's inside?
When you select files FastSum computes their checksums according to the MD5 checksum algorithm, which can be easily compared with previously computed checksums or stored for future integrity checking. There are two most important MD5 checksum properties for the end-user: the fixed size and the non-discoverability. The first property means that it does not matter how big the source file is, it always has a short 128bit MD5 checksum value that can be compactly stored and easily shared. While the second property implies that a pair of nonidentical files will have different MD5 checksum value i.e. even a short fixed size value is enough for detecting changes within the file.

Home Page - https://www.fastsum.com/