Question 1

Do my files get uploaded anywhere?

Accepted Answer

No. Everything happens in your browser using the File System Access API and Web Crypto. Your files are read locally, hashed on a background thread, and never sent to any server. There is no backend.

Question 2

How do you decide two files are duplicates?

Accepted Answer

For exact duplicates we compute a SHA-256 hash of each file's full contents — identical hashes mean identical bytes, regardless of file name or location. We also flag near-duplicates that share a name and size but differ in content, so you can review those yourself.

Question 3

What happens to the duplicates I don't keep?

Accepted Answer

Nothing is deleted from your original folders — the tool never modifies your input. It produces a fresh output containing one copy of every unique file. For each duplicate group you choose which copy to keep.

Question 4

Can I find duplicates inside a single folder?

Accepted Answer

Yes. Add just one folder and every file inside it — subfolders included — is content-hashed, so internal duplicates are grouped exactly the same way. Add more folders any time to merge across them too.

Question 5

How do I get the merged result out?

Accepted Answer

In Chrome and Edge you can write the deduped set straight into a folder you pick. In any browser you can download a .zip of the unique files plus a merge-report.txt summarizing what was merged.

Question 6

How big can the folders be?

Accepted Answer

Hashing runs in a Web Worker with chunked reads, so the UI stays responsive on thousands of files and multi-gigabyte inputs. Very large jobs are limited mainly by your device's memory and disk speed.