Find duplicate files

Only files with exactly the same content, byte for byte. Names, folders and dates are ignored for matching. Files are grouped by size first; only files that share a size with another file are hashed with SHA-256, and equal hashes of equal size are reported as one group. Similar photos, re-encoded videos or edited documents are not detected.

No. It never changes your files. The CSV report lists every group with the path, size, modified date and time (as your device shows it, with its offset from UTC, so Excel shows the time you see here), SHA-256 and the action (keep or duplicate) so you can remove copies with your own file manager. The ZIP contains the kept copy of each group plus every file that had no duplicate.

Empty files all have the same content, so two or more of them form a group like any other.

Files are not read when you choose them. Only files that have the same size as another file are read, one at a time, to compare their contents, and the ZIP of kept files reads each kept file once while it is made, so the practical limit is the size of that ZIP in your device's memory. Hashing runs at the speed of your browser's built-in cryptography; a few hundred megabytes take seconds.

Desktop browsers with folder access can copy kept files, including their sub-folders, into an empty destination folder. Only one file is read at a time. Each copy is checked against the destination after its file is read and again just before it is saved: a file of the same name that is already there, or appears there during the copy, stops the copying and is left as it is, and the page says how many copies were completed. The browser gives a page no way to lock a folder or to create a file only where none is, so two cases escape that check and are replaced by the copy: an empty file another program makes at that name in the instant between the page's look and its creation of the copy, which cannot be told from the page's own new file, and a file written there in the very instant a copy is saved. Originals are never changed. A printable cleanup review records every decision and full SHA-256 hash.

No. The page loads a small script into your browser and every operation runs on your device. You can check this yourself in the browser's network panel: after the page has loaded there are no upload requests. Closing the tab discards the file.

No. These basic tools are free, have no limits set by us and store nothing on our servers. The practical limit is your device's memory for very large files.

Nothing you open or type. While the tab is open, the tool pages keep a short list of the steps taken in it, in the tab's session storage: the step (page opened, started, succeeded, first success, used again or failed), the tool's name, the time, how many files were used and, for a failure, an error code; never a file name, the contents of a file or your text. It holds at most the latest 200 steps, and the browser deletes it when the tab closes. The page never sends it. Where a Report a problem button is shown, you can attach the last 20 steps to your report; nothing is attached unless you tick that box. In local storage the page keeps only choices you made: a Light or Dark theme until you choose System again, the language you picked with the EN / 中文 switch if it differs from your browser's language, and this tool in your recently used list if you switched that list on at the tools page.