Calculate MD5, SHA1, CRC32 checksum and batch check multiple files.
Checksum Calculator is a free file checksum calculation software, it can support for MD5, SHA1, CRC32 checksum, and can batch check multiple files. This freeware is completely free and easy to use very much.
This downloads and installs quickly and has a comprehensive but simple UI. I used it to check a directory with 1700 files for duplicates, the filenames were not useful. You can add a whole directory, run the program, save the results, import into excel as a CSV, sort on the check sums, check each checksum against the next cell and count the TRUE results.