ToolBox FreeTEXT TOOL
Text Diff Checker
Paste an original and a changed version to see exactly what was added and removed, line by line or word by word.
Additions are shown in green and start with “+”. Removals are shown in red with a strike-through (or start with “−” in line mode).
How to use the Text Diff Checker
Paste the older text on the left and the newer text on the right, pick Lines or Words, and choose Compare. In line mode each line is marked with + (added), - (removed) or a space (unchanged). Word mode shows the whole text with changed words highlighted, which is better for prose.
The comparison uses a longest-common-subsequence algorithm, the same idea behind most diff tools, so moved or edited text is shown as a removal plus an addition.
Examples and uses
Original The cat sat on the mat versus changed The cat slept on the mat in word mode shows “sat” removed and “slept” added.
Limitations and good to know
To keep your browser responsive there is a size limit; if the texts are too large you will be asked to compare smaller sections. This tool compares plain text only and does not understand document formatting. It highlights differences but cannot judge which version is correct.
Frequently asked questions
Is anything uploaded?
No. Both texts stay in your browser.
Why is an edited line shown as removed and added?
A diff records changes as deletions and insertions. An edited line is a deletion of the old line plus an insertion of the new one.
Can colour-blind users read it?
Yes. Additions and removals are also marked with “+” and “−” symbols or strike-through, not colour alone.
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