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How to Sign a PDF on Mac

A simple step-by-step guide to sign a pdf on Mac using PDFWix's free online tools.

How to Sign a PDF on Mac

Sign a PDF on macOS using Apple Preview's signature trackpad capture, or PDFWix in Safari. Free, no install, no signup, no watermark, works on every Mac.

How it works

  1. Open in Preview — Double-click the PDF — it opens in Preview by default.
  2. Open Markup — Click the Markup toolbar icon (pencil tip) to reveal the annotation tools.
  3. Create or pick a signature — Click the Signature icon, then Create Signature via Trackpad, Camera, or iPhone — or pick a previously saved one.
  4. Place and resize — Drag the signature onto the signature line and resize using the corner handles.
  5. Save — Press Cmd-S — Preview flattens the signature into the PDF, ready to send.

Frequently asked questions

What's the easiest way to sign a PDF on Mac?

Open the PDF in Preview, click the Markup toolbar (pencil tip), click the Signature icon, capture your signature once via Trackpad / Camera / iPhone, drag it onto the page, and Cmd-S to save. Built in since OS X Yosemite, still the best option on Sequoia in 2026.

Is Mac Preview's signature feature legally valid?

Yes — Preview produces a simple electronic signature flattened into the PDF, which meets U.S. ESIGN Act and eIDAS basic-signature requirements. Sufficient for the vast majority of contracts. Advanced or qualified signatures need a dedicated trust service provider.

Why use PDFWix to sign on a Mac if Preview already does it?

On your own Mac, you usually shouldn't — Preview is excellent. PDFWix is for signing on a borrowed Mac without storing your signature in their Preview, or signing inside a browser workflow without breaking out to a separate app.