Text Diff Checker
Compare two blocks of text line by line and see exactly what was added, removed, or unchanged.
How to use this tool
Paste the original text on top and the changed text below, then click Compare. Removed lines show in red, added lines in green.
About this tool
Uses a longest-common-subsequence (LCS) line-matching algorithm — the same category of algorithm used by tools like "diff" and Git — to find the minimal set of added/removed lines between the two texts.
100% client-side. Neither text is uploaded, logged, or stored.
Frequently asked questions
Does this compare word-by-word or line-by-line?
Line-by-line. Each line is compared as a whole unit; if even one character on a line differs, the whole line shows as removed and added.
Is there a size limit?
The comparison algorithm runs in your browser and its time/memory grows with the number of lines in each input, so very large documents (several thousand lines) may be slow. For typical code snippets, config files, or paragraphs, it's instant.