Diff Checker

About the Diff Checker

When two versions of something look almost identical, finding what actually changed by eye is slow and unreliable. This Diff Checker does it instantly: paste an original and a revised version, and every added, removed, and changed line is highlighted — right down to the individual words that differ within a changed line.

It runs entirely in your browser. Your text — a contract redline, a config change, an edited essay, a code snippet — is never uploaded or logged, so even sensitive comparisons stay private.

What it shows

• Line-level diff using a proper longest-common-subsequence algorithm, so unchanged lines stay aligned and only real changes are flagged.
• Word-level highlighting inside changed lines, so you see exactly which words were swapped instead of a whole line lighting up red and green.
• Side-by-side or inline views — compare in two columns, or read a single unified stream with + and - markers.
• Change stats — a quick count of additions, deletions, and unchanged lines, with an "identical" badge when the two match.

Options

• Ignore case — treat Hello and hello as the same.
• Ignore whitespace — focus on real content changes, not reformatting or indentation.
• Ignore blank lines — skip empty-line noise between paragraphs.
• Swap — flip the two sides if you pasted them the wrong way around.

Common uses

• Compare two drafts of an article, contract, or email to see precisely what an editor changed.
• Spot the difference between two config files, log lines, or environment files.
• Review a code snippet against an earlier version without opening a full diff tool.
• Check that a copy-paste actually matches the original, character for character.

No account, no upload — paste, compare, done.

Related tools