How to use Compare PDF
- Choose the original PDF, then the revised one. Use ↑ ↓ if they are the wrong way round.
- Press Compare PDFs. The words and every page are compared on your device.
- Read the highlighted changes side by side, switch to Overlay to see what moved, or open the list of changes.
How the two files are compared
| Check | What it finds |
|---|---|
| Words | The text of both files is read in reading order and compared word by word. Added words are marked green on the revised page, removed words red on the original. A change in the middle of a sentence shows as one removed and one added run. |
| How each page looks | Each pair of pages is drawn and compared pixel by pixel. Areas that look different are shaded, which catches changed pictures, logos, signatures, stamps, drawings and text that moved, even where the words are the same. |
| Pages | Pages are matched by the words they share, so a page added or removed in the middle shows as added or removed, and the rest still line up. |
| Document properties | Title, author, the app that made the file and its dates, side by side, with the ones that differ marked. |
Reading the result
- Side by side puts each original page next to its revised version, with the changed words boxed and the areas that look different shaded.
- Overlay draws both versions in one picture: ink only in the original is red, ink only in the revised version is blue, and what both share is grey. It shows moved and resized content at a glance.
- List of changes gives every change in order, with its page numbers. Click one to jump to it.
Good to know
- Text that is part of a picture, such as a scanned page, isn't read as words. Recognise text in Edit PDF first if you need it compared word by word.
- The same words set in a new font or at a new size are not counted as a text change, but the page will show as looking different.
- Very long documents take longer, because every page is drawn twice on your device.
Your files stay private
EditPDF Online runs in your browser on Windows, Mac, Linux, iPhone and Android, using open-source libraries. Your documents are never uploaded, stored or seen by us.
Frequently asked questions
Does it find changes in pictures and layout?
Yes. Every page is also compared as an image, so a changed picture, drawing, signature or stamp, or text that moved, is marked even where the words are the same.
Can it compare scanned PDFs?
Scans have no text, so only how the pages look is compared: changed areas are marked, but changes cannot be listed word by word. Run Recognise text in Edit PDF on both files first if you need the words.
What if pages were added or removed?
Pages are matched by their words, so an inserted page shows as added and the pages after it still line up with their counterparts.
Can I keep a record of the changes?
Yes. Download report saves a text file with the totals and every change, made on your device.
Is this tool really free?
Yes. It is free with no signup, no watermark and no daily limits.
Are my files uploaded to a server?
No. All processing happens in your browser, so your files never leave your device.