Paste two versions of text or code to see exactly what changed, line by line.
A diff checker compares two pieces of text line by line and shows exactly what's different — which lines were added, which were removed, and which stayed the same. It's the same kind of comparison git shows for code changes, generalized to any text: contracts, config files, articles, two drafts of an email.
The comparison uses the Longest Common Subsequence (LCS) algorithm — the same technique behind most diff tools, including git — to find the longest sequence of lines that appears, in order, in both texts. Everything not part of that shared sequence is marked as either added (only in the new text) or removed (only in the original).
This means a line moved to a different position but otherwise unchanged may show as a removal and an addition rather than a single "moved" marker — line-based diffing tracks content and order, not relocation specifically.
Comparing two short paragraphs:
Line by line — a single changed word within a line marks that whole line as changed (shown as a removed old line plus an added new line), rather than highlighting just the changed word.
Yes — paste the two versions of a file to see exactly what changed, the same way a git diff would show it.
No — a line that differs only in trailing spaces or indentation is still treated as changed, matching how most diff tools behave by default.
Yes — each side is capped at 2,000 lines, since the comparison algorithm's cost grows with the product of both lengths.
No — the comparison runs entirely in your browser.