PDFStack Tool
Compare PDF — Side-by-Side PDF Diff Tool Free
Upload two versions of a PDF and compare them page by page. PDFStack renders both documents at high resolution so you can visually inspect differences between versions — useful for contract revisions, document proofing, and version control.
Open Compare PDF →
No file uploads
No account required
Free to use
Private & secure
When do you need to compare PDFs?
Legal documents, contracts, and technical specifications go through multiple revisions. Being able to quickly see what changed between Version A and Version B saves time and prevents costly oversights. PDFStack renders both as images for a clean visual diff.
How to compare two PDFs
- 1Open Compare PDF in PDFStack.
- 2Upload both PDF files (original and revised version).
- 3Click Compare PDFs.
- 4Download the rendered page images and inspect them side by side.
All processing happens locally in your browser — no files are uploaded to any server.
Common Uses
Comparing contract drafts, proofing a revised brochure, checking a report against the previous version, verifying that a PDF hasn't been altered.
Frequently Asked Questions
Does it highlight changes automatically?
PDFStack renders both documents as images for visual comparison. Automatic change highlighting requires a server-side diff engine.
How many pages can I compare?
All pages of both documents are rendered — no limit.
What resolution are the comparison images?
Pages are rendered at 2× scale (144 DPI) for clear comparison.
Is it private?
Yes. Both PDFs are processed entirely in your browser.