See exactly what changed between two versions of any text
Paste the original on the left. Paste the modified version on the right. Hit Compare. You get a color-coded diff: green for added lines, red for removed lines, and everything else stays neutral. It uses the Longest Common Subsequence algorithm: the same approach behind git diff and Unix diff. So the output isn’t just technically correct, it’s minimal, showing the fewest changes needed to go from version A to version B.
What you get
- Line-by-line comparison with color-coded output
- Green (+) marks additions, red (-) marks removals
- LCS algorithm for accurate, minimal diffs
- Works with code, prose, config files, data, any text
- Handles thousands of lines
- Both texts stay in your browser. Nothing transmitted.
How to use it
Left box: original text. Right box: modified text. Click Compare. Scroll through the output.
Say you’ve updated a configuration file and want to see exactly what changed. Paste the old version on the left, new version on the right. The diff output highlights every added, removed, or changed setting, no manual file scanning required.
Where this saves time
Code review without Git: sometimes you just have two versions of a file and want to see the diff. Maybe it’s a file a colleague emailed you, or a code snippet from a Stack Overflow answer you modified.
Document versioning: comparing draft versions of an article, a contract, or a report. See exactly what your editor changed in your manuscript.
Config auditing: production config vs. staging config. What’s different? Paste both, find out in seconds.
API testing: compare expected vs. actual API responses. Discrepancies jump out immediately in the diff view.
Verifying find-and-replace: after using the Find and Replace tool on a large document, paste the before and after here to make sure only the intended changes were made. Trust but verify.
One thing to watch for: if your two texts use different line endings (Unix \n vs Windows \r\n), every single line will show as changed even when the content is identical. Make sure they match.
FAQ
What algorithm does it use?
The Longest Common Subsequence (LCS) algorithm. It’s the same foundation as Git diff and Unix diff. Produces the minimal set of changes needed to transform one text into the other.
Can I compare code?
Absolutely. Code, config files, SQL queries, JSON, anything line-based. The output format is the standard way code changes are reviewed everywhere.
How big can the inputs be?
It runs in your browser, so thousands of lines work fine. Tens of thousands might take a moment depending on your device. No hard limit.
Does it highlight character-level changes within a line?
Currently it operates at the line level: it tells you which lines changed, not which specific characters within a line. This matches standard diff behavior.
Is it safe for sensitive documents?
Yes. Both texts stay in your browser. Nothing is ever transmitted to a server. Safe for code, contracts, confidential content.