How to Compare Two Folders Online
Upload Folder A (the original or baseline) and Folder B (the updated or target version). Click Compare to generate a color-coded report showing:
- Missing files — present in A but not in B
- Added files — present in B but not in A
- Modified files — same path but different size or timestamp
- Unchanged files — identical in both folders
The comparison uses relative paths and works even if the root folder names differ. Everything runs in your browser — no files are uploaded.
Common Use Cases
Backup Verification — Ensure every file copied correctly to an external drive or cloud storage.
Website Deployment — Check that no files are missing or outdated before going live.
Code Migration — Confirm nothing was lost when moving a project to a new repository.
Sync Auditing — Find files that cloud sync tools (Dropbox, OneDrive, etc.) missed.
How the Comparison Works
The tool builds an index of all files using their relative paths as keys. It then compares file size and last-modified timestamp for each path. A 2-second tolerance accounts for filesystem timestamp differences. The entire process is fast even with thousands of files.
Frequently Asked Questions
It compares file size and last-modified timestamp. If either differs (with a 2-second tolerance), the file is marked as modified.
Yes. The indexed approach is very efficient — even 10,000+ files compare in under a second.
No. It runs entirely in your browser using the HTML5 File API. Works in Chrome, Firefox, Edge, and Safari on desktop.
No. All comparison happens locally. The tool reads only metadata (path, size, timestamp) — never file contents.