Duplicate File Finder — Free, Runs in Your Browser

Photo libraries, Downloads folders and backups fill up with copies: the same file saved twice, imported from two phones, or copied "just in case". This tool finds byte-for-byte identical files, even when their names are different.

How to find duplicate files

1. Click choose a folder and confirm access. Subfolders are included.
2. Wait for the scan — you'll see progress as it compares files.
3. Review the groups, sorted by wasted space (biggest wins first).
4. Export the list (.csv) if you want to work through it in a spreadsheet.

Your browser reads the files locally. Nothing is uploaded, and the folder is only accessible for this one scan.

How it decides two files are the same

Comparing names is unreliable (photo.jpg and photo (1).jpg may differ; IMG_1.jpg and holiday.jpg may be identical). Instead it works in three passes:

1. Size — files of different sizes can't be identical. This rules out most files instantly.
2. Quick fingerprint — a SHA-256 hash of the first 64 KB of each same-size file.
3. Full fingerprint — a SHA-256 hash of the whole file, only for files that matched so far.

Two files with the same full SHA-256 hash are, for all practical purposes, identical.

Limits

• A browser can find duplicates but can't delete them — you'll remove them in File Explorer or Finder.
• Files over 1 GB are skipped at the full-hash step to keep memory use sane.
• It finds exact copies only. A resized or re-saved version of a photo is a different file.

Deleting safely, and finding similar photos

Duplicate File Finder & Photo Cleaner for Windows scans multiple folders fast, also finds visually similar photos (different sizes or formats of the same shot), lets you keep the newest or oldest copy per group, and moves the rest to the Recycle Bin so mistakes are recoverable. For a full picture of your drive, DiskAtlas Pro adds a treemap and cleanup suggestions.