Text Diff

Line-by-line comparison of two texts, marking added and removed lines; long unchanged runs are collapsed.

What this tool does

Aligns two texts line by line: - marks lines only in the original, + marks added lines, and a space prefix means unchanged. The algorithm is longest common subsequence (LCS) — the same family as git diff's line comparison. Long unchanged runs collapse into “… (N unchanged lines) …” so the differences stand out. Everything is computed locally, so contracts and unpublished drafts never leave your device.

Typical use cases

A counterparty sends back an edited contract — paste both versions and see exactly which lines moved; diff two config files to find the line that broke production; compare two versions of a code snippet; verify what changed between two drafts; even check suspected plagiarism by seeing how much text overlaps.

Caveats

This is a line-level diff: changing one character within a line shows as one removed line plus one added line, rather than highlighting the character. Trailing spaces and tab-vs-space differences are reported faithfully. For performance, each side is limited to 800 lines. Windows line endings (\r\n) are normalized automatically.