File Duplicate Finder
Choose a folder or drop files to find exact duplicates, however they are named. Files are compared by content: first by size, then by a quick fingerprint of their beginning and end, and finally by a full SHA-256 hash, so even thousands of photos or documents are checked efficiently. Identical files are grouped with the space their extra copies occupy, and nothing is uploaded or deleted.
- Runs in your browser
- No sign-up
- Free to use
How to use File Duplicate Finder
- Choose a folder, or drop files (you can add several batches).
- Click Find duplicates.
- Review each group of identical files.
- Download the CSV report and remove copies yourself.
File Duplicate Finder features
Content comparison
SHA-256 hashes, so renamed copies are found too.
Fast on large sets
Size and edge fingerprints avoid hashing unique files.
Folders
Choose a whole folder, including subfolders.
Wasted space
Shows how much space redundant copies use.
Same-name check
Optionally lists files that share a name but differ.
Local and safe
Nothing is uploaded, and nothing is deleted.
When to use File Duplicate Finder
- Cleaning up a photo library with repeated imports.
- Finding copies of documents spread over several folders.
- Freeing space on a full drive or cloud folder.
- Checking a backup for files stored twice.
File Duplicate Finder FAQ
Is the comparison done locally or on a server?
Locally. Files are read and hashed in your browser; their contents never leave your device.
How reliable is a SHA-256 match?
Two different files having the same SHA-256 hash is practically impossible, so files in one group are identical byte for byte.
Does it find similar photos?
No. It finds exact copies. Resized or re-saved photos have different bytes and are not reported.
Will it delete anything?
No. Browsers cannot delete files on your disk. Review the groups and delete copies yourself; the CSV suggests which file to keep.
How many files can I check?
Up to 20,000 files at once. Large files take longer because they must be read completely when another file has the same size and fingerprint.
Why are empty files ignored?
All empty files are identical, which is rarely useful. Untick the option to include them.
Finding duplicates by content
Duplicate files accumulate quietly: photos imported twice, attachments saved in several folders, downloads repeated, backups copied into backups. They waste space and cause confusion about which copy is current. Names are no help, because copies are often renamed, and different files often share names like IMG_0001.jpg. The only reliable test is the content.
Comparing every file with every other would be slow, so the finder works in stages. Two files can only be identical if they have exactly the same size, which removes most files immediately. For files that share a size, a fingerprint of the first and last 64 kilobytes is calculated, which separates most remaining files cheaply. Only files that still match are read completely and hashed with SHA-256.
SHA-256 is a cryptographic hash: any difference in content, even a single bit, produces a completely different value, and finding two different files with the same hash is beyond any practical computation. Files in the same group are therefore identical byte for byte, which the tool states as a fact rather than an estimate.
Results are grouped and sorted by the space the extra copies use, so the biggest savings come first. The optional same-name check lists files that share a name but differ in content, which is useful when consolidating folders. A CSV report lists every file with its group and hash and suggests one copy to keep.
Everything runs in your browser, which means private files are never uploaded. It also means the tool cannot delete or move files on your disk; use the report to clean up in your file manager, and keep a backup until you are sure.