Text diff checker

Spot the differences instantly

Paste the original text on the left and the changed version on the right, then tap Compare. Added lines are highlighted in green, removed lines in red, so the changes jump out instead of forcing you to read both versions side by side. It uses a line-by-line longest-common-subsequence diff — the same core idea behind the diffs in version control — and runs entirely in your browser, so confidential text stays on your device.

When a diff saves you

A diff is the fastest way to answer "what actually changed?" — between two drafts of a document, two versions of a config file, two copies of a contract, or a chunk of code before and after an edit. The human eye is bad at catching a single altered word in a wall of text; a diff finds it immediately. It's also a quick sanity check before sending: paste your edited version against the original to confirm you changed exactly what you meant to and nothing more.

Reading the result

Because this is a line-based diff, it compares whole lines rather than individual words — a line with one changed character shows as a removed line and an added line. That keeps the output simple and predictable, and it matches how most code review tools work. For the cleanest results, paste text that's already broken into lines (paragraphs, list items, code) rather than one long run-on block. To reshape text before comparing, the text transformer can normalise case and whitespace.