Anti-Twin vs fclones

Anti-Twin searches hard disks and other storage locations for duplicate or similar files. It can compare names, check file contents byte by byte, search for binary similarity, and compare images by their pixels. The image method can find similar pictures even when they have different compression rates or file formats. Search locations include local drives, USB flash disks, memory cards, shared network folders, and a second folder or path. Results can be selected automatically, exported as an Excel file, and sent to the Recycle Bin or deleted.

The program is free for private use and dates to 2003. The download page lists 32-bit and 64-bit Windows, and says it can run through Wine on Linux or Mac and on ReactOS. It can also be installed and started from a USB memory stick. Anti-Twin does not search the Internet or FTP servers, excludes files larger than 2 GB from comparisons, and has no restore function for deleted files. The site says it was maintained until 2012 and still runs on Windows 10 and 11.

fclones is a free command-line utility for locating groups of identical files and handling redundant copies. It runs on Linux, macOS, and Windows, and can scan multiple directory roots, standard-input file lists, and mounted or removable devices. Search controls include recursion limits, glob and regular-expression filters, and minimum or maximum file sizes. It can compare files using size, inode or file identifiers, prefix and suffix hashes, and full-content hashes. Results are available as text, fdupes-compatible output, CSV, or JSON. Once duplicates are identified, fclones can remove or move them, or replace them with soft or hard links. On supported file systems, it can deduplicate file data with native copy-on-write reflinks, a capability unavailable on Windows. Users can inspect and alter duplicate lists before removal, and dry-run mode reports changes without executing them. The Rust implementation parallelizes I/O and CPU-heavy work and adjusts processing for SSDs and HDDs. Optional persistent hash caching can help repeated scans and resumed work; the project is released under the MIT license.