Need to verify that a PDF has not been altered since you sent it? A visual diff comparison can expose unauthorized text changes, added stamps, removed signatures, or modified numbers — visible as red highlights in the diff view.
Any change to a PDF — even a single digit in a price, a changed name, or a removed clause — alters the visual appearance of that region. A pixel diff comparison highlights these changes precisely, even if they are subtle.
Before sending or sharing a PDF, save an unmodified reference copy in a secure location. This is the file you will compare against if you need to verify authenticity later.
Go to pdfeditor.onl/compare-pdf. Upload your reference copy as PDF A and the version you want to verify as PDF B. Click Compare.
If the document is unaltered, the diff pages will appear mostly in uniform grayscale with very few or no red highlights (minor compression noise is normal). Any significant red regions indicate content that differs from the original.
Tip: Pay particular attention to number fields (prices, dates, amounts), signature areas, and clauses near the end of contracts — these are the most commonly targeted areas in document fraud.
Download the diff report PDF as a formal record. The report shows the change percentage per page and highlights all affected regions — useful for legal or compliance purposes.
A clean diff confirms the visual content is identical to the reference copy. It does not verify cryptographic integrity (which requires a digital signature embedded at creation time). For legally binding authenticity, use certified digital signatures.
No. The comparison is visual/pixel-based and does not read PDF metadata, timestamps, or hidden streams. Only visually rendered content is compared.