How this diff checker works
The tool finds the longest common subsequence of lines shared between the two texts, then marks everything else as added or removed — the same core approach behind diff and Git's line-level diffs. Lines that moved without changing still show as unchanged if they appear in the same relative order.
Line diff vs. word diff
This compares whole lines, not individual words or characters — a single changed word marks the entire line as changed. That's the right granularity for comparing config files, code, or paragraphs where line boundaries matter; it's less useful for spotting a one-word edit inside a long paragraph.
Frequently asked questions
Why does a single edited word mark the whole line as changed?
This is a line-level diff, so it compares entire lines for equality — if any character differs, the whole line is treated as removed-then-added, matching how tools like git diff present line changes by default.
Does whitespace count as a difference?
Yes — trailing spaces or different indentation will make otherwise-identical lines show as changed, since the comparison is exact. Trim or reformat both inputs first if you only care about content, not formatting.
Is my text uploaded when I use this tool?
No. Comparison happens instantly in your browser — nothing is sent to a server.