Sign a PDF online — privately

How to sign a PDF on Windows, Mac, and iPhone

Windows: Edge and Chrome can open a PDF, but placing a clean signature still usually means print-to-PDF gymnastics or a paid tool. PDF Boost AI runs in the same browser you already have.

Mac: Preview can sign. It is fine for a one-off. It is not a tool you send to a client on Windows.

iPhone: Markup works. It also lives inside Files and Mail in ways that are easy to lose. A browser tab that does the same job on every device is less tribal knowledge.

PDF Boost AI’s signature is an image stamp, not a cryptographic certificate. For qualified eIDAS or DocuSign-style audit trails, use a dedicated signing platform — and keep this tool for the everyday “I agree” page.

What this is (and isn’t)

This is a private, visual signature. Courts and counterparties often accept it for informal agreements and internal forms. It is not a certificate-backed digital signature and does not embed a cryptographic identity.

Place the mark, download, and — if you need to send it — attach the file to mail from your own account. PDF Boost AI does not email on your behalf, which is the point.

Questions

Does a drawn signature count as legally binding?

In many everyday contexts, a shown intent to sign is what matters. PDF Boost AI is not a law firm. For high-stakes or regulated documents, use a qualified signing service.

Can I upload a signature PNG instead of drawing?

Not yet. Draw in the pad. A stylus on a tablet works well.

Is the signed file uploaded?

No. The PNG never leaves the tab except as pixels inside the PDF you download.