How to compare two texts
- Paste the original on the left and the new version on the right.
- Read the result: removed lines are red, added lines green, and changed words inside a line are highlighted.
- Turn on “Show changes only” for long documents.
How the comparison works
The tool finds the longest common subsequence of lines, the largest set of lines that appear in both texts in the same order, the same idea used by programmers' “diff” tools. Everything else is an addition or a deletion. Changed lines are then compared word by word.
Example
A shop updates its notice: “opens at 9:00” becomes “opens at 8:30”, and “over 50 euros” becomes “over 40 euros”. The tool highlights exactly those numbers, so you can confirm nothing else was changed by mistake.
Uses
- Contracts and policies: see what changed between two versions before signing.
- Editing: check what a co-author or an AI tool changed in your draft.
- Translations and subtitles: find missing or extra lines.
- Code and configuration: spot the one changed setting.
Frequently asked questions
Is this a plagiarism checker?
No. It compares two texts you provide; it doesn't search the internet.
Can I compare Word or PDF files?
Copy the text out of the files and paste it here. Formatting (bold, fonts) is not compared.
Does it work with Arabic?
Yes, each line is shown in its natural direction.
Is my text uploaded?
No. Confidential documents stay on your device.
Sources: Hunt J. W., McIlroy M. D., “An Algorithm for Differential File Comparison”, Bell Labs, 1976; Myers E. W., “An O(ND) Difference Algorithm and Its Variations”, Algorithmica, 1986.
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Last reviewed: 2026-11-02. Results are calculated in your browser and may differ slightly from other apps. See our disclaimer.