Duplicate File Finder
Find duplicate files by comparing sizes and SHA-256 hashes. Drop multiple files, see which are identical, group duplicates, and export results. Partial-hash (first 4KB) for speed, full-hash for confirmation. 100% client-side.
About Duplicate File Finder
Find duplicate files by comparing sizes and SHA-256 hashes. Drop multiple files, see which are identical, group duplicates, and export results. Partial-hash (first 4KB) for speed, full-hash for confirmation. 100% client-side. Everything runs locally in your browser — your data never leaves your device.
How to use
- Enter your input in the tool above.
- Adjust any options to your preference.
- Use the Copy or Download buttons to save the result.
- Everything happens locally — your data never leaves your browser.
FAQ
What does the Duplicate File Finder do?
It scans the files you drop, groups them by size, and for any files sharing a size, computes a SHA-256 hash to confirm whether they are byte-for-byte identical. You get a list of duplicate groups with file paths, sizes, and how much space you'd save by removing the extras.
Why does it use a partial hash first?
Computing SHA-256 on large files is slow. We hash only the first 4KB of each file as a quick filter — only if two files share both their size AND their first-4KB hash do we compute the full SHA-256 to confirm. This makes scanning 100s of files dramatically faster.
What hash algorithm is used?
SHA-256 via the browser's built-in WebCrypto API. This is the same primitive used for file integrity verification and TLS certificates.
Can I delete the duplicates?
Yes, on Chromium browsers with the File System Access API you can open a folder and delete the duplicate files in-place. On other browsers, you can export the duplicate list (CSV or JSON) and delete manually.
What extra features does this tool have?
10 extras: (1) Drag-drop multiple files at once. (2) Progress bar during scan. (3) Partial-hash (first 4KB) quick filter. (4) Full-hash confirmation only when needed. (5) Live stats (total files, duplicates found, space saved). (6) Filter by size threshold (ignore files < N KB). (7) Sort by size / name / date. (8) Export as CSV or JSON. (9) History (localStorage — last 10 scans). (10) Shareable URL with scan settings.
Are my files uploaded anywhere?
No. All hashing runs in your browser using WebCrypto. Your files never leave your device.
What's the maximum number of files?
There's no hard limit, but scanning 1000+ large files may take a while and use significant memory. We process files in chunks and show progress.
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