Compare PDF — Spot Every Difference Between Two Documents
Load the original and the revised version of a PDF and see exactly what changed. Every page is shown side by side with a red overlay marking the differing pixels and a percentage score for the page. It is a fast way to confirm an edit only touched what it should have — all rendered and compared locally in your browser.
Frequently Asked Questions About Comparing PDFs
How does Compare PDF work?
Both PDFs are rendered page by page with pdf.js in your browser. Matching pages are aligned to the same scale and their pixels are compared, producing a similarity score, a percentage of changed pixels, and a red difference overlay for every page.
What can I use it for?
Verify that a revised document only changed the intended section, check that a re-exported file kept its content, or confirm two copies of a contract are identical before signing.
Are there file size limits?
No hard limits — the only constraint is your device memory. Larger documents simply take a little longer to render and compare locally.
What does the overall similarity mean?
It is the average of every page pair’s matching-pixel ratio. A score of 100% means every compared page matches perfectly; pages present in only one document pull the score down.