Side-by-side text comparison with highlighted differences
A text diff tool compares two versions of a document side by side and highlights what changed. Useful for spotting subtle edits in contracts, validating that a copy-paste didn't drop characters, comparing config files between environments, or reviewing AI-edited prose.
This diff runs entirely in your browser — paste original on the left, modified on the right, and see additions, deletions, and changes color-coded line by line. Sensitive content (legal text, internal configs) never leaves your device.
Original:
function greet(name) {
return "Hello, " + name;
}
Modified:
function greet(name) {
return `Hello, ${name}!`;
}Line 2: removed return "Hello, " + name;
Line 2: added return `Hello, ${name}!`;Both. Lines are matched first (so a re-ordered paragraph shows as moved, not as a giant rewrite), then within each changed line we highlight the specific characters that differ.
Not currently — the diff is exact. If trailing-space differences are noise for your use case, run the text through a normalizer first (or use a CLI diff with --ignore-trailing-space).
Paste only. For files, open them in any editor and copy the contents. For very large files (megabytes) the in-browser diff will be slow — use git diff or a desktop diff tool instead.
No hard limit, but performance degrades past ~10,000 lines. The diff algorithm is O(n × d) where d is the edit distance — small differences in large files are still fast; large differences in large files can take seconds.
Same purpose, different algorithm. git diff uses the Myers algorithm with several heuristics tuned for code; this tool uses a similar line-based approach. For reviewing actual git history, use git diff itself — it understands renames and merges.