This is a win32 console application. There is no GUI, but you can use Explorer to drag files over md5sums.exe to obtain their md5 hashes.
MD5sums calculates the MD5 message digest for one or more files (includes a percent done display for large files). By comparing the MD5 digest of a file to a value supplied by the original sender, you can make sure that files you download are free from damage and tampering. MD5 values are frequently supplied along with downloadable files. (Optimized implementation).