Free · Private · In your browser

Compare PDF

Render two PDFs side by side page by page to spot visual differences.

Drop your files here, or click to browse
Processed on your device — nothing is uploaded

How your files are handled

We built these tools so you never have to wonder where your documents go. Here is exactly what happens when you use them.

  • Your files are processed entirely in your browser using open-source libraries (pdf-lib, PDF.js, and others).
  • Nothing is uploaded to our servers. We have no backend that receives, stores, or scans your documents.
  • We cannot see, store, or access your files — not during processing, not after, not ever.
  • Processing uses your device's memory and CPU. Large files may take longer, especially on phones and tablets.
  • All tools are free with no paywall tricks, no hourly task limits, and no watermarks on your output files.

How it works

Three simple steps. Your files never leave your device, and the result downloads straight to your computer or phone.

Frequently asked questions

Common questions about privacy, pricing, and how these tools work.

More optimize tools

Other free PDF utilities that work the same way — private, in-browser, no sign-up.

How to compare PDF

Compare PDF shows two documents side by side and highlights where they differ. It is a visual, pixel-based comparison that is good for spotting changes between two versions.

  1. Add PDF A and PDF B; both are rendered on your device and never uploaded.
  2. Page through the documents using the previous and next buttons.
  3. Click Show differences to overlay the changed pixels in red.
  4. Download the difference image for any page you want to keep.

Everything happens in your browser — your file is never uploaded, and there is no sign-up, watermark, or limit.

Frequently asked questions

Are my files uploaded to a server?

No. Every tool runs entirely in your browser using open-source libraries, so your file is processed on your own device and is never uploaded. We have no backend that receives, stores, or scans your documents.

Is it really free, and will there be a watermark?

Yes. There is no account, no sign-up, and no hourly limit, and the tools never add a watermark to your output. UnboundPDF is free and is not affiliated with Adobe.

Does it work on a phone or tablet?

Yes. The tools run in any modern mobile browser as well as on desktop. Because the work uses your device's own memory and processor, very large files simply take longer on phones.

Is this a text comparison or a visual one?

It is a visual, pixel-by-pixel comparison. It highlights anywhere the two pages look different, rather than diffing the underlying text word by word.

What do the red areas mean?

Red marks the pixels that changed between PDF A and PDF B on that page, and a percentage shows how much of the page differs.