Text Diff Checker
Compare two blocks of text and see exactly what changed, line by line. Great for diffing code, config, or copy — computed locally with no server round-trip.
About Text Diff Checker
A diff checker compares two versions of text and highlights exactly which lines were added or removed. It's the fastest way to spot what changed between two config files, two API responses, or two drafts of a paragraph. This tool uses a longest-common-subsequence algorithm to line up unchanged lines, and runs entirely in your browser.
Frequently asked questions
Does it diff word by word or line by line?+
Line by line. Each line is marked added, removed, or unchanged — ideal for code and config where lines are the natural unit.
Is there a size limit?+
It's meant for the sizes you'd paste by hand. Very large inputs (tens of thousands of lines) can get slow because the algorithm compares every line pair.
Is my text sent anywhere?+
No. The comparison runs locally, so it's safe for diffing private code or configuration.