This tool allows you to generate hashes of files using your browser. A file hash aka checksum is a short string which summarizes the content of the file. Often when downloading large files, you will want to compute a checksum for a file, to help check that the file was not tampered with in some way.
Checksums are much smaller than the original file. While most modifications to the file will result in a radically different checksum, this is not always true. MD5, and old and now obsolete checksum, has been ‘broken’. Attackers that want to tamper with files can produce a set of targetted changes that modify the file, yet still result in the same md5 hash.