How it works
Both texts are split into lines and matched with a longest-common-subsequence comparison, the same idea behind classic diff tools. Unchanged lines show plainly, removed lines are red with − and added lines are green with +. Long unchanged stretches collapse so the actual changes stand out.
old vs new → − removed · + added · counts on top
When to use the options
- Ignore case: compare “Hello” and “hello” as the same line.
- Ignore whitespace: overlook extra spaces and tabs, so reformatted code still matches.
Tips
- For config files and code, compare before pasting to catch exactly what changed.
- Moved blocks show as removed in one place and added in another — that is expected with line comparison.
- Everything runs in your browser; nothing is uploaded.
Standards and sources
- Line comparison follows the longest-common-subsequence method used by classic diff utilities
Last reviewed October 12, 2026
Frequently asked questions
How is the comparison done?
Both texts are split into lines and matched with a longest-common-subsequence comparison, the same approach classic diff tools use. Equal lines stay plain while changes get − and + markers.
Why does a moved paragraph show twice?
Line comparison has no memory of moves: a block moved elsewhere counts as removed in the old spot and added in the new one. The content is the same, only its position changed.
What are the size limits?
Up to 1,000 lines or 100 KB per side. Larger inputs are refused so the page stays responsive.
Is my text sent anywhere?
No. The whole comparison runs in your browser and nothing leaves your device.