Text Diff Checker
Paste the original text on the left and the changed text on the right, then press Compare. Lines only in the new version are marked +, lines removed are marked −, and unchanged lines are kept for context.
This tool runs in an isolated frame on tools.freetoolspro.com. Your files and inputs stay on your device, and advertising on this page cannot read them.
Method
The diff is the longest common subsequence of lines, the same principle behind classic diff tools. Whitespace and case differences count as changes. Each side may have up to 4,000 lines.
Privacy
Your text is processed by a Web Worker inside the isolated tools.freetoolspro.com frame. It is not uploaded, logged or shown to advertising scripts on this page, and it is gone when you close the tab.
Common questions
Can it compare words within a line?
Not yet; a changed line is shown as one removal and one addition.
Is my text stored?
No. Close the tab and both texts are gone.
Methodology reviewed 2026-10-27. Processing details and test approach.