Compare PDFs

How to compare two PDFs

1. Choose the original PDF on the left and the changed one on the right.
2. Press "Compare PDFs".
3. Review each page below — anything that changed is highlighted in red.

Which version is the one you agreed to

A contract comes back "with a couple of small changes", a quote is re-sent, a policy is renewed. The change that matters is rarely announced: a figure, a date, a clause that lost a "not". Reading both copies side by side is how it gets missed.

How the comparison works

Both documents are drawn page by page in your browser and the pages are compared pixel by pixel; anything that differs beyond a small threshold is marked. That catches a changed number, a moved comma and a replaced logo alike, and pages that exist in only one of the two files are shown as added or removed.

Limits

It compares what the pages look like, not the words, so a different font or text that reflows marks a whole paragraph as changed even when it reads the same. Scans of the same page shifted a millimetre will show noise along the edges. When you need the difference word by word, get the text out of both with PDF to text and compare that.

How does the comparison work?

robinpdf renders both PDFs page by page and compares them pixel by pixel, right inside your browser. Wherever the two differ, those areas are marked in red over the changed version, so edits, moved text and added or removed elements are easy to spot. Nothing is uploaded.

Is it private?

Yes. Everything runs inside your web browser, using your own device. Nothing is uploaded to any server, so your documents stay completely private. How does this work without uploading?

Frequently asked questions

Is it free and private?

Yes. Both files are compared entirely in your browser — nothing is ever uploaded.

What if the PDFs have a different number of pages?

Extra pages are listed too, marked as added or removed, so you can see structural changes as well as content changes.