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

Every platform has a “good enough” way to sign a PDF, and none of them agree with each other. That is how a one-page NDA turns into a 20-minute thread.

Windows

Edge and Chrome open PDFs. Microsoft’s in-Edge signature tools exist; they are easy to miss and they are not what your Mac counterpart is looking at. Print-to-PDF after signing in Word is the folk method. It works. It also produces a second file with a new filename that nobody filed.

Mac

Preview remains the most humane built-in signer. Trackpad signatures look like they were drawn by a ghost. A photograph of a wet-ink signature looks better and still is not a certificate. Fine for internal forms.

iPhone

Markup in Files or Mail is genuinely good. The failure mode is losing the signed copy inside a thread. Save to Files immediately, then share from there.

One method that matches on every device

A browser tool that stamps a drawn signature onto a page — locally — is boring in the best way. Same control, same download, same privacy story on Windows, Mac, and phone. It is not a qualified electronic signature. For a lease or a stock grant, use a real signing platform. For the other 90% of pages that say “sign here,” it is enough.