Duplicate File Finder

Select a batch of files and find exact duplicates by comparing MD5 content hashes — even when the file names are different. Free and private: everything is hashed locally in your browser, nothing is uploaded.

🗂️ Drop files here to compare

or click to browse — add as many files as you like, in several batches · stays on your device

How to find duplicate files

  1. Add your files. Drag and drop files into the box above or click to browse. You can add several batches — for example the contents of two different folders — and remove individual files from the list.
  2. Start the scan. Press Find duplicates. The tool first compares file sizes, then computes an MD5 hash of the content of every file that shares its size with another, so identical files are found no matter what they are named.
  3. Review the duplicate groups. Identical files are shown grouped together with their size, hash and the disk space you could reclaim. Copy or download the report, then delete the extra copies on your device.

About this tool

This free online duplicate file finder detects identical files by their content, not their name. Photos copied from a camera twice, "document (1).pdf" downloads, backups scattered across folders — duplicates quietly eat disk space. The scanner uses a two-step approach for speed: files are first grouped by exact byte size (files of different sizes can never be identical), and only the remaining candidates are hashed with MD5 in 2 MB chunks, so even multi-gigabyte videos can be checked without freezing the browser.

Unlike installable duplicate cleaners, nothing here ever leaves your computer: file contents are read and hashed locally in your browser with JavaScript, and no data is uploaded, stored or logged. The tool never deletes anything either — it only reports which files are identical, and you stay in full control of the cleanup.

Frequently asked questions

How does the tool detect duplicates?

Files are first grouped by exact size in bytes. For each group of same-size files, the tool computes an MD5 hash of the full file content, reading the file in 2 MB chunks. Files with the same size and the same hash are byte-for-byte identical, regardless of their names or modification dates.

Can two different files be reported as duplicates by mistake?

Practically no. A false positive would require two files of exactly the same size that also collide in MD5 by accident — the odds are around 1 in 264 even before the size check. Engineered MD5 collisions exist in cryptography, but they don't occur by chance in normal files.

Are my files uploaded anywhere?

No. Hashing happens entirely in your browser using the JavaScript File API and the SparkMD5 library served from this site. Your files are read locally chunk by chunk and never transmitted — the scan even works offline once the page has loaded.

Can I scan a whole folder, and will files be deleted?

Browsers can't recursively walk folders from this kind of page, but you can open a folder in the file picker and press Ctrl+A (Cmd+A on Mac) to add everything inside it, repeating for each folder you want to compare. The tool only reports duplicates — deleting the extra copies is always done by you, manually, on your own device.