How to View PDF Side-by-Side in Two Windows

Category: PDF Office Tips Updated: 2026-06

In daily work or academic research, we often need to compare two PDF documents, such as checking old vs. new contract clauses, proofreading translation drafts against original documents, or reviewing print design proofs. Switching back and forth in a single window is highly inefficient and error-prone. Below is a detailed guide on how to view PDF documents in a dual-pane layout with synchronized scrolling.

🛠️ Quick Steps to Compare PDFs Side by Side

Open the Side-by-Side Viewer

Click the prominent call-to-action button at the top or bottom of this page to go to the homepage of the it365 Document Side-by-Side Viewer.

Import Both PDF Files

In the left and right panels, click the "Import File" button, or drag and drop your two PDF files directly into the dashed upload areas.

Enable Sync Scroll

Once the files are loaded, turn on the "Sync Scroll" switch in the top toolbar. Now, scrolling either PDF file will automatically scroll the other pane.

Adjust & Swap Freely

Use the "Zoom" dropdown menu in either pane to adjust the size (e.g., Fit Width). If needed, click the "Swap Position" button to swap the panes without re-uploading.

No Plugins Needed, Runs 100% Locally

Start using the it365 online tool to view and compare your PDF files side by side right now!

Start PDF Side-by-Side Comparison Now

❓ Frequently Asked Questions (FAQ)

Q Can I view a Word file on the left and a PDF file on the right?

Absolutely! Our side-by-side viewer supports not only identical formats (like two PDFs or two Word files) but also mixed comparisons between Word and PDF files. You can open a Word file on the left and a PDF on the right, and edit the Word file directly in the browser while scrolling in sync.

Q Will my PDF files be uploaded to a server? Is it secure?

100% Secure & Private. This tool uses pure client-side technology. Your PDFs are read and rendered entirely within your local browser memory. No data is ever uploaded to our servers. You can even use it offline, guaranteeing absolute privacy for business contracts and personal documents.

Q Can I align scrolling if my PDFs have different lengths or page counts?

Yes. We provide two scroll-locking mechanisms:

Offset Scroll (Recommended): Manually align the left and right pages to the desired sections first. The tool will then lock this initial offset and scroll both sides with the exact same pixel delta.
Absolute Scroll: Proportional locking. Scrolling either side to any height (e.g., 50%) instantly aligns the other pane to the exact same percentage, perfect for highly similar versions.

Q Can I copy text from the PDFs while viewing them side by side?

Yes. The tool renders high-fidelity text layers over the PDF pages. You can select, highlight, and copy text from either pane just like in a standard PDF viewer, without degrading pages into non-editable images.