Duplicate File Finder
Find exact duplicate files by content hash - fully offline
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
About this tool
Scans a set of files and identifies exact duplicates by comparing their content hash (not just filename) - fully offline, useful for cleaning up storage space by finding truly identical files even if they've been renamed or moved to different folders.
How to use this tool
- Select files or foldersChoose the dataset you want to scan for duplicate content.
- Hash and compare contentsCompute file fingerprints and group exact matches.
- Review duplicate groupsInspect candidate sets before deciding which copy to keep.
- Cleanup safelyDelete/move redundant files after validating canonical versions.
Deleting duplicates safely
Files are matched by a hash of their content, so two files are flagged only when they are byte-for-byte identical - renamed copies are found, but an edited or resized copy is not. Before deleting, decide which copy to keep: usually the one in the folder you actually use.
Keep a backup until you have checked that nothing you need has gone.
Key features
- Finds true duplicates independent of filename/path differences.
- Saves storage and reduces archive clutter effectively.
- Offline hashing preserves privacy for local files.
- Useful for backups, media libraries, and document repositories.
Common uses
- Cleaning duplicate photos across import folders.
- Deduplicating backup snapshots before long-term storage.
- Removing repeated documents from shared drives.
- Auditing mirrored project folders for redundant binaries.
Tips for better results
- Review duplicate groups manually before deletion.
- Keep earliest or highest-quality canonical copy.
- Backup critical folders before bulk cleanup.
- Use folder tags/naming after cleanup to avoid re-duplication.
Mistakes to avoid
- Deleting duplicates blindly without checking context differences.
- Assuming similar names imply identical content.
- Removing files linked by external applications unintentionally.
- Skipping backup before large-scale deduplication operations.
Frequently asked questions
It compares each file's content hash (a fingerprint generated from the file's actual data) rather than the filename - two files with completely different names but identical content will have the same hash and be flagged as duplicates.
No - the tool works fully offline, processing files directly on your device to compute hashes and compare them; nothing is uploaded to a server.
No - hash comparison is exact; even a single-byte difference produces a completely different hash, so only truly byte-for-byte identical files will be flagged as duplicates.
Keep one copy in the folder you actually use, delete the others, and empty the recycle bin only after checking nothing broke. Back up first if the files matter, such as family photos.
No. Content hashing finds exact copies only; an edited, resized or re-saved photo is a different file. Finding visually similar images needs a dedicated photo deduplication app.
Repeated downloads, phone backups imported more than once, email attachments saved in several folders, and cloud sync conflicts. Downloads and photo folders are the best places to start.