Software to find duplicate files
© 2012, Aidex GmbH, Jörg Rosenthal
Anti-Twin first appeared in 2003 and was maintained until 2012. However, the program still runs on current Windows versions such as Windows 10 or 11 and can therefore still be downloaded here.

Anti-Twin Classic

Byte-by-byte comparison of user-defined files (file content)
Search for identical or similar file names
Pixel-based image comparison, e.g. search for similar pictures

Freeware for private use

Anti-Twin is a small software application which compares files, i.e. it searches for duplicate or similar files on your hard disk drive. All similar or identical files that were found can either be sent to the recycle bin or directly deleted. This will increase the hard disk space on your computer.

Select the option “Compare file content” to compare the entire binary content of the files. This means that the file names are irrelevant. Here, the basic principle is: “Names are just smoke and mirrors. It's the inner values that count!”

Application examples

Check existing file collections for contained duplicates
Check new files before they are to be sorted into a folder (e.g. new MP3 files or pictures are to be included in an archive)
Synchronize folders manually, e.g. compare similar folders on laptop and PC
You can't optimize Windows with it!

Anti-Twin is an excellent tool to e.g. find and delete duplicate MP3 files in a download folder or to find similar images. Apart from that, Anti-Twin helps you clean up employees' chaotic file repositories in company networks, e.g. by searching for unnecessary file copies and redundant data backups.

Anti-Twin is freeware and can be downloaded from the download page (see also menu above). Please also read the instructions and note the warnings.

Screenshot of Anti-Twin

Michael from Australia wrote:
Dear Jörg, I just want to thank you for this fantastic, bug free and easy to use software. Over the last week I have spent many hours buying three software packages to sort through 60,000 duplicate photo files (all the other software packages would would run for many hours, one run for 18 hours to simply crash and they all cost me together just under $100). Your software took less than two hours cleaned up half the collection with NO MISTAKES. I am so happy to see simple software that simply does the job. I am happy to donate money to you as you saved me many more frustrating hours and maybe more wasted money. Let me know what money would make you happy within reason lol and I will be happy to send to you or if you want a gift or something from Australia simply let me know.
Thanks again, I love the software, Michael

Freeware comparison tool: Find duplicate files and folders, or search similar images pixel-based! Keep your computer waste files free, detect file doublets and check file doubles, file equivalent or file pendant, dupe file search e.g. MP3 songs or downloaded photos, reduce clutter on your disks, scan and clean your hard disk, sort out cloned files, save disk space, kill repeated files, increase your hard disk space (Disk drive cleaning software kit). Manually locating similar images may be fine if you have a just dozen files. But what if you have a hundred? A software utility to seek file copies, garbage collection, identify duplicate and similar files, select multiple files to locate a file counterpart or a file copy, file deduplication, compare files by name or content, de-dupe at file level, check identical files, superfluous doubles finder and redundant files killer. The clone finder program analyzes their contents and locates files that look alike. Our dupe eliminator program matches byte by byte to give you most accurate result. Faster and more reliable than other duplicate file finders. Free download!