Duplicate File Finder .NET is definitely one of the best. Unlike other dupe detection programs that can only do the search by CRC/MD5 or byte-by-byte comparison, Duplicate File Finder .NET uses much more efficient algorithms. It has two groups of algorithms. The first group (universal algorithms) is designed for analyzing both text files (txt, doc, rtf, html, asp, php, etc.) and binary data (exe, com, jpg, gif, mp3, mpg, etc.) This group of algorithms is most efficient at analyzing binary files.