Can I compare two PDFs for differences?

Someone sends back a contract and says they only fixed a typo. You would like to be sure. Reading two copies side by side is slow, and the eye skips what it expects to see. A tool can read both files and list every word that differs.

PDF Compare does that in your browser. This guide shows the steps, what the tool counts as a change, what it cannot see, and what to do when a comparison looks wrong.

Can I compare two PDFs for differences?

Yes. Add the older file as Original and the newer file as Revised. PDF Compare reads the words of both, then marks each word added, removed or changed. The two sides scroll together, and a list of changes jumps to each one. Looking at the comparison is free.

It works on PDFs that have real text, which covers most files made on a computer. A scan is a picture of a page and has no words to compare. More on that below.

How do I compare two PDFs step by step?

Drop the older file on Original and the newer file on Revised, read the summary, move through the changes one by one, and download the redline if you want to send it on. The text of each file is read in your browser.

1. Open PDF Compare. Drop the older version on Original and the newer version on Revised, or choose them from your device.
2. Wait for the text of both files to be read. A long document takes a moment.
3. Read the summary. It counts the words added, removed and changed, and the pages they are on.
4. Scroll the two sides together. Removed words are red and struck through on the Original, and added words are highlighted on the Revised.
5. Click a change in the list to jump straight to it. Check each one against what you were told had changed.
6. If you want to share the result, press Download redline PDF.

What counts as a difference?

It counts words. A new word is added, a missing word is removed, and one word swapped for another is changed. Line breaks, extra spaces and words split by a hyphen at the end of a line do not count, so a file that was only reflowed shows no changes.

• Compared: the text, word by word, across the whole document.
• Not compared: pictures, drawings, fonts and layout.
• A sentence that moved shows as removed in one place and added in the other.

What do I get to download?

You get two files from one download. The redline PDF is your revised file with the changes marked as standard PDF annotations. The change report is a short PDF that lists every change with its page. The download counts as one use.

Send both to the other person, or open the redline in PDF Annotator and add your own comments first. If you are a freelancer, see the freelancer page. If you rent out a unit, see the landlord page.

A worked example

Dana is a freelance designer. She sends a four-page service contract and the client returns a file with the note that only the logo changed. She adds her copy as Original and theirs as Revised.

The summary lists a few words added and removed on two pages. She clicks the first change in the list and sees "30 days" struck through in red on the Original and "60 days" highlighted on the Revised, in the payment terms. The second change is a new sentence in the termination clause. The logo is a picture, so the tool does not report it.

Dana downloads the redline and replies with both changes marked, asking the client to confirm. Nobody signs until everyone has agreed on the version. If the file is an agreement you also need to sign, see how to fill out and sign a freelancer NDA as a PDF.

Should I ignore case and punctuation?

Two options help when a file was retyped. Ignore upper and lower case treats Rent and rent as the same word. Ignore punctuation treats days. and days, as the same word. Leave both off when capitals or commas matter, as they can in a contract or lease.

Landlords can use the same steps on a lease. Compare last year's with this year's, then see a free rental lease agreement you can fill in as a PDF.

Common problems and fixes

• It says there is no text to compare. The file is probably a scan. Run it through OCR PDF, which makes the words searchable, then compare the new file.
• Only some pages were compared. A page with no text, such as a scanned signature page, is left out of the comparison, so read that page yourself.
• A changed logo, chart or photo does not show. Only the text is compared, so look at those pages by eye.
• A moved paragraph looks like two changes. That is how a move reads word by word: removed in one place, added in the other.
• The colors look reversed. You may have added the files the wrong way round. Remove each and add them again, older on Original and newer on Revised.
• It could not read the text of a file. Check that the file opens in a PDF app, then try again.

Where does your file go?

Contracts and leases hold names, prices and addresses. PDF Compare opens and compares both files in your browser tab, and the redline and report are made there too. Nothing is sent to our servers. Even so, it is worth checking how any tool you use handles files like these.

A short checklist

• Put the older file on Original and the newer file on Revised.
• Check that both files have real text, not a scan.
• Click through every change in the list.
• Look at pictures, signatures and layout yourself.
• Share the redline and report, and keep both originals.

2 free uses in total, no account needed. Free files can be up to 50 MB, and Pro allows up to 500 MB.

Sources

• PDFinish's own PDF Compare page, for the modes, the options, the downloads and the limits, as of November 2026.