Document Diff

Each document's text is extracted — from the Word or OpenDocument file's content, from the PDF's text layer, or from the plain text — and split into paragraphs. The paragraphs are compared in order to find those that stayed the same, those that were added or removed, and those that were changed. Inside a changed paragraph, the words are compared too, so you see the exact edit rather than a whole paragraph marked red and green.

The comparison looks at the words, not at fonts, colours, spacing or page layout, so reformatting a document does not show up as a change — which is usually what you want when checking content. Pictures, comments and tracked-change markup are not compared. Word's own Compare feature can also show formatting changes if you need them. For PDFs, the text layer is compared, so scanned PDFs without text need PDF OCR first.

Because only the text is compared, you can check a PDF against the Word document it was made from, a web page against a draft, or an RTF export against the original. Line breaks inside a paragraph can differ between formats — PDFs often break lines where the page did — so very long PDF paragraphs may appear as several lines. Turn on Ignore upper / lower case if capitalisation doesn't matter for your check.

Review the changes in a returned contract, lease or agreement before signing; check what an editor or colleague changed in a report; compare two versions of a policy, terms of service or thesis chapter; confirm that a published PDF matches the approved text; or find what changed between two exports of the same document. The HTML report is useful to attach to an email or keep with the file.

Contracts and drafts are confidential, so both documents are read and compared on your device. Nothing is uploaded, stored or logged. Documents up to 100 MB each can be opened. To compare pasted text instead of files, use the Text Diff Checker; to compare PDFs page by page as pictures, use Compare PDF.