Compare two PDFs

When a text comparison saves you

Reading two versions of a long document side by side is slow, and the eye skips exactly the small edits that matter: a "shall" that became a "may", a deadline that moved from 30 to 45 days, a sentence dropped from a warranty. A word-level comparison finds those in seconds. People use it to:

• Check a contract redline. The other side sends a "final" version. Compare it with the last draft you agreed to, so you know that only the changes you discussed were made, even if tracked changes were accepted before it reached you.
• See what changed in a policy. Employee handbooks, terms of service, insurance policies at renewal and lease renewals rarely come with a list of changes.
• Proofread a typeset proof. Compare the printer’s proof with the approved manuscript PDF to catch dropped lines and new typos before the job is printed.
• Track a revised tender or filing. Addenda, amended filings and new versions of a specification.

What it compares, and what it doesn’t

Line breaks and spacing never count: a paragraph that wraps differently because the margins or font changed is still the same paragraph. A word split by a hyphen at the end of a line is joined back up, and two-column pages are read one column at a time.

How to read the results

The inline view shows the new version, with the words that were taken out struck through in red and the words that were put in underlined in green. A replaced word shows both: "within thirty (30) forty-five (45) days". The side by side view puts the original on the left and the changed version on the right, kept level paragraph by paragraph so you can scroll both at once; on a phone the two versions are stacked.

The summary counts the words added and removed and the paragraphs touched. Next change outlines each change in turn and tells you its page in both documents, which is what you need to discuss it with someone holding a printed copy. For a long document, Hide unchanged text folds the paragraphs that didn’t change, leaving only the edits.

Tips for a cleaner comparison

• Leave headers and footers out (the default). Otherwise a running title that changed from "Draft 3" to "Final" shows up as a change on every page. The option lists the lines it found, so you can check that nothing real is being skipped.
• Ignore case and punctuation when one version was retyped or reformatted and you only care about wording. Leave them on for a legal or proofreading check, where a comma can matter.
• Compare like with like. Two exports from the same program give the cleanest result. If one version is a scan, get the original file instead.
• Mark your own drafts. Stamp working copies with a DRAFT watermark, or number production sets with Bates numbering; both are skipped as repeating lines when you compare.

Private by design

Most online comparison services upload both documents to their servers, which is a poor fit for unsigned contracts, settlement drafts or anything under a confidentiality agreement. Here the PDFs are opened by PDF.js, Mozilla’s open-source PDF reader, running in your browser, and the comparison runs in a background thread of the same page. No file, page text or file name is sent anywhere, and closing the tab clears everything.

Need the text itself? Copy it out with PDF to text. To check layout and images by eye, turn pages into pictures with PDF to JPG.