How to use
- Choose the left folder and the right folder.
- Choose Quick (size and date) or Exact (content hash) comparison.
- Filter the result by status and export it.
Worked example
The sample compares a card folder with its backup: IMG_4832.JPG has the same size but different content, stock-log.txt is only on the card, notes.txt is only in the backup, and two photos are identical.
Supported formats and limits
| Input | Two folders |
|---|---|
| Output | Comparison table (CSV) |
| Limits | Up to 50,000 files per side. |
| Engine | Relative-path matching, then size; Exact mode hashes same-size pairs with SHA-256 (hash-wasm) in a Web Worker, Quick mode compares modified times within 2 seconds |
Limitations
- Modified dates can change when files are copied, so Exact mode compares content.
- Files are matched by relative path (optionally ignoring letter case); a renamed or moved file shows as only left plus only right.
Questions
What is the difference between Exact and Quick?
Exact hashes every same-size pair with SHA-256, so it detects changed content even when the size is the same. Quick compares size and modified time (within 2 seconds); it is faster, but copying can change modified dates.
What about renamed or moved files?
Files are matched by relative path, optionally ignoring letter case, so a renamed or moved file shows as only left plus only right.
Guides
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