Paste an original and a revised version to see exactly what was added or removed, word by word.
Paste the earlier version into the left box and the newer version into the right, then run the comparison. The output marks what was removed and what was added, and keeps the unchanged words in place so you can read the result as a sentence rather than as two separate paragraphs.
Work on one section at a time. A whole contract against a whole contract produces a wall of marks in which the two changes you care about are invisible. A single clause against its revision shows you exactly what moved.
Original: Payment is due within 30 days.
Revision: Payment is due within 45 days of invoice.
The comparison finds two edits, not a rewritten sentence. The number changes from 30 to 45, and the phrase of invoice is added at the end. Everything else — Payment is due within and days — is unchanged and shown as such.
That distinction is the point. A word processor's track changes will show you the same thing, but only if the other side used track changes. Pasting two plain-text versions catches the edit made silently, which is the one that costs money.
The comparison is word by word, not letter by letter. It finds the longest run of words the two versions share and treats everything between those runs as a change. So a typo inside a long word shows up as the whole word removed and the corrected word added, which is correct but coarser than a character diff. For proofreading spelling, read the marked version with your eyes on the words, not on the colours.
Order matters to this kind of comparison. Move a paragraph from the top of the page to the bottom and the tool reports it twice: once as removed where it used to be and once as added where it now is. It is not wrong, but it is not telling you that the paragraph is the same text in a new home. If a document was reorganised, expect a lot of marks and read for content instead of counting them.
The tool compares exactly what you give it, including capitalisation and punctuation. Total and total are different words to it. If you only want to know whether the wording changed and not how it was typed, that strictness is helpful. If you are checking a cleanup pass, it will flag every comma you fixed.
The comparison builds a grid with one row and one column per word, so the work grows with the square of the length. Long documents would freeze the tab. Split anything over roughly 3,000 words per side.
Not on this page. Normalise both sides first if case should not count — the case converter can lower-case both versions without touching word order.
No. It compares two texts, not two authors. Version history belongs in your editor or your shared drive.
No. It is a reading aid that shows differences quickly. For a contract, have the actual document reviewed by someone qualified; this page does not interpret what a changed clause means.
No. Both comparisons happen in the browser and nothing is stored or transmitted.
The comparison is this page’s word diff. It is not a legal redline and not a programmer’s line diff.
Last updated: November 2, 2026. Reviewed by David Liu.