Text Diff Checker
Paste an original and a changed version of any text to instantly see a colour-coded, line-level diff. The tool uses an LCS algorithm to align the two inputs, marking added lines in green, removed lines in red, and unchanged lines in grey, with counts of each. Everything runs locally in your browser, so your content never leaves your device.
Examples
Original: apple banana cherry
apple - banana + blueberry cherry
How it works
The two texts are compared line by line. The tool finds the longest run of lines that appear in both versions in the same order and treats those as unchanged. Everything else is marked: a minus for lines only in the original, a plus for lines only in the changed version.
Because the comparison works on whole lines, a line with one altered word shows up as a removed line followed by an added line; the changed word itself is not highlighted. Lines must match exactly, so a different capital letter or a trailing space counts as a change.
The summary counts added, removed and unchanged lines. Very long inputs, several thousand lines on each side, take noticeably longer because every line is checked against every other.
How to use Text Diff Checker
Why use this tool
Frequently asked questions
It performs a line-level diff, comparing the two inputs one line at a time using an LCS algorithm.
No. All comparison happens locally in your browser and nothing is sent to a server.
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