Workload
Hundreds of gigabytes of video, in mixed formats and re-encodes
A library that grew over years collects the same source several times over: an original, an export, a copy someone sent back, a version made to fit an older device. None of them share a byte, so a checksum sees four unrelated files and a filename tells you nothing. Dup's job here is to collapse each of those clusters down to the one copy worth keeping.
The same footage does not look the same to a checksum
Dup fingerprints what a video looks like frame by frame, not what its bytes are. That is what lets a 4K ProRes master match its H.264 export, a 1080p re-encode and the MP4 that came back off a phone. Container, codec, resolution and bitrate can all differ and the match still holds.
Compare before you commit
Every group opens side by side: frames from each file, with duration, resolution, size and format underneath. Auto-Keep marks the best copy in each group by the rule you set once, and you review its choices rather than making thousands of them yourself.
Get it back if you were wrong
Dup shows the size of what is about to go before it goes, and says plainly whether a file is heading for the Trash or being removed for good. Deletions land in the Trash by default, so the Finder can put them back.
Sized for a library that does not fit on the boot drive
Point it at an external drive or a NAS volume the same way you point it at a folder. The scan runs across every core the Mac has, reports progress as it goes, and never claims a clean result for a folder it could not read.
Your files never leave your Mac. Dup processes everything locally: no uploads, no cloud, no tracking.
Try it on one folder
Free to try, with 250 MB of cleanup included. Nothing leaves your Mac, on any plan.
macOS 13+