Text Diff Checker

About the Text Diff Checker

This compares two pieces of text and highlights exactly what changed between them — what was added and what was removed. It's the quick way to spot the difference between two drafts of a document, two versions of a config or code snippet, an original and an edited paragraph, or a copy someone claims is identical. Paste the old text on one side and the new on the other, and the changes light up.

How it works

The two inputs are compared with a proper diff algorithm (the diff library) and the result is shown inline: added content is marked as an insertion and removed content as a deletion, with unchanged text left plain. You choose the granularity:

• By word — highlights the specific words that changed, best for prose.
• By line — compares whole lines, best for lists, code and structured text.
• By character — the finest level, catching single-character edits like a typo or a changed digit.

The comparison updates live as you type or paste, and text is HTML-escaped so it displays literally.

Assumptions and behaviour

• It's a two-way comparison of A versus B, showing what it takes to get from the first to the second.
• Word mode breaks on whitespace boundaries; line mode on line breaks; character mode compares every character.
• Additions and removals are marked distinctly; anything unchanged is shown as-is.
• Both inputs are treated as plain text; any HTML is escaped and shown, not rendered.

Limitations

• It highlights differences; it doesn't merge them. There's no three-way merge, patch file, or "apply changes" — it's for reviewing, not resolving.
• Diff results can look busier than the 'real' edit. A block that was moved shows as a deletion in one place and an addition in another, since the algorithm compares sequences rather than understanding intent.
• Character mode on large texts is heavier to compute and can produce very granular, noisy highlighting; word or line mode is usually clearer.
• It compares the text you paste; it doesn't diff files directly or show side-by-side line numbers.

Privacy

The comparison runs entirely in your browser. Both texts are never uploaded or stored.