How to sign a PDF on a Mac with Preview (nothing to install)

On a Mac you don't need to download anything to sign a PDF. Preview, the app that opens PDFs by default, has a signing tool that stores your signature so you can reuse it on any document.

1. Open the PDF in Preview. 2. Click the Markup button (the pen icon) to show the toolbar. 3. Click the signature button and choose "Create Signature". 4. Create the signature using one of three methods (below). 5. Select it, drag it onto the line and resize it. 6. Save with Cmd + S.

Trackpad: sign with your finger on the trackpad; press a key to finish. Camera: sign on white paper and hold it up to the camera, and Preview crops the ink automatically. iPhone or iPad: if they're on the same account, sign on the phone's screen and it appears on the Mac.

The camera usually gives the result closest to your real signature; the iPhone, the most convenient.

Preview pastes an image of your signature onto the PDF. It's perfect for signing yourself, but it doesn't record who signed or when, and it doesn't let someone without your Mac sign.

For client contracts or documents several people must sign, use an electronic signature platform: each signer gets their link, signs from any device — Mac, Windows or phone — and the document ends up with an audit certificate.