Compare two blocks of text and see a line-by-line diff showing what was added, removed or kept the same. It is the quick way to spot changes between two versions of a config file, a copied paragraph, a log excerpt or any pasted content when you do not have a full version control diff handy. This checker uses a longest-common-subsequence comparison, the same core idea behind standard diff tools, so it aligns matching lines correctly instead of naively comparing line by position. Added lines are marked in one color and removed lines in another. Paste the original on the left and the new version on the right, then compare. All processing runs in your browser, so your text never leaves your device.