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

Knowing how to sign a PDF on a Mac can significantly boost your productivity, especially if you work remotely or need secure document handling. No more printing, scanning, and signing documents with a pen. Mac users can quickly sign a PDF using built-in tools for basic signatures or more advanced third-party apps for greater security and efficiency.

In this article, I’ll show you how to sign a PDF on a Mac using different methods, including your trackpad, camera, iPhone, or iPad, and how to insert digital signatures securely.

How to sign a PDF securely on Mac

When you learn how to sign a PDF document on a Mac, security should be the first thing on your mind — especially when you’re dealing with sensitive contracts or financial documents. The built-in way to sign documents on a MacBook is through Preview. It’s an easy and free option, but a traditional Preview signature can be risky in certain contexts.

Key risks include:

• Unauthorized access if someone uses your Mac. Preview saves your signature in the Markup menu. On the one hand, this lets you easily reuse it in the future. On the other hand, it creates a potential vulnerability. If someone wanted to steal your signature, Preview would probably be the first place they’d look.
• The ability to reuse signatures without additional protection.
• The absence of encryption or audit tracking, which is especially risky for sensitive documents.

This doesn’t mean you shouldn’t use Preview to sign PDFs on a Mac. You can! And I'll show you how. My position is simply that you should filter your documents. Non-sensitive or less important files can be signed using the basic built-in method. 

But documents that require extra protection should be signed with more secure tools. For sensitive files, I use Nitro PDF Pro to digitally sign PDF on Mac. It offers encryption, verified workflows, secure PDF editing and signing.

After you install Nitro PDF Pro, you'll be able to apply a few types of signatures.

• Regular signature. Click Form > Signature. Click anywhere in the document and draw your signature using the trackpad or mouse. After you click OK, the signature is saved, and you can move it anywhere on the page. However, it is not saved for future use unless you right-click on it and select "Save to Library". In this case, the signature will go to the Library (a button in the upper right corner), and you can paste it from there in the future.

• Nitro Sign. This tool adds a layer of security to the signing process. Only people who have received your email invitation can sign the document. On your end, you can track when the recipient views and signs the document, check if there are other contracts in the queue to be signed, and more. Nitro Sign requires a separate subscription with a 14-day free trial period.

In addition to signing documents, Nitro PDF Pro lets you reorder pages, merge separate documents, redact sensitive information, recognize text in images with OCR technology, and more. Imagine doing all the paperwork you'll ever need to do in one app.

How to digitally sign a PDF in Preview on Mac

Preview (the same app you use to open images) is the best choice for quick signing needs, basic forms, or simple documents that don’t require advanced editing or encryption. This method is good for simple signing tasks and fast edits. (However, keep in mind the security points above.)

Here's how to sign a PDF document on Mac with Preview:

1. Open your PDF with Preview.
2. Click the icon with the pencil in a circle in the upper right corner (Markup menu).
3. Click the signature icon > Click Here To Begin and draw a signature using your trackpad.
4. Press any button to finish.
5. Click Done.
6. Put the signature in place (you can resize it by dragging the corners) and click off.

How to sign a PDF on Mac using a trackpad

You can create a MacBook signature for a PDF file using your trackpad without opening a PDF. This signature will be saved, and later, when you open a PDF, it will be right in the signature menu in the Markup tool. You will be able to quickly insert it into the document.

Here is how to create a reusable signature with a trackpad:

1. Open Preview from Applications.
2. In the menu bar, navigate to Tools > Annotate > Signature > Manage Signatures.
3. Select Click Here to Begin and start drawing on the trackpad.
4. Press any button when finished.
5. Click Clear to start over or Done if you like the result. 

Note that your trackpad is literally represented on a screen, so treat it like a piece of paper and your finger (or stylus) like a pen. Each movement will be displayed on the screen.

How to sign PDF on Mac using a camera scan

If you don’t like scribbling your signature on the screen, you can use the old method — put your signature on paper and then scan it with your camera.  

To scan your physical signature:  

1. Open PDF in Preview > Markup > Create Signature.
2. Navigate to the Camera tab and hold your physical signature up to the camera, aligning it with the baseline.
3. When your signature is recognized, click Done.

Then place it in the desired location as usual.

This signature often looks more natural than one drawn on a trackpad because, honestly, signing your name with your finger on a trackpad isn’t the most convenient thing you’ll ever do on a Mac. If your trackpad signature looks clunky or jagged, that’s okay — you’re not alone. If you want a clean, paper-like signature captured from your real handwriting, this is the way to go.

How to sign PDFs directly in the Mail app on Mac

The Mail app on a Mac lets you sign PDFs without downloading attachments or switching between apps, which makes your workflow much faster. I find this method perfect for quick approvals, urgent documents, or situations when a signature is needed right here, right now.

That said, I don’t consider it especially secure. I wouldn’t use it for highly sensitive documents. But for urgent situations and non-critical files, it’s perfectly fine.

Here's how to sign PDF on Mac without leaving the Mail app. 

1. Open Mail and start a new message (⌘ + N).
2. Drag a PDF file into it.
3. Hover over the PDF, click the dropdown arrow, and choose Markup.
4. Repeat the same process as shown above for Preview.
5. Click Done.  

How to insert a saved signature into a PDF on Mac

Remember I said that PDF editors allow you to store signatures right inside them? This means that a third party who opens the app may be able to use the signature saved in it.

To avoid this, you can save your signature in a separate file and keep it in a secure place — for example, in a password-protected folder or encrypted location. This way, you can manage, update, or replace it whenever needed. 

Here's how to create a PNG with your signature and digitally sign PDF on Mac with it:

1. Create a signature in a drawing app or scan your physical signature with a camera or import it from any other tool. Basically, it's just an image with your signature on it.
2. Save your signature as a separate file: Edit > Export as .png.
3. Open the saved file with your signature, right-click on the image, and select Copy Subject.
4. Open the PDF file and press Command + V to paste the signature.

You'll need to resize the signature and place it where you want it on the page. 

What about security? Read our tutorial on how to password-protect a folder on a Mac.

How to sign a PDF on iPhone and iPad using Markup

Now that you know how to sign documents on a Mac, you can forget about the pen-and-paper method. It’s really not necessary to travel anywhere just to sign docs. And you know what’s even more convenient? Signing docs on the go! This is possible if you learn how to sign PDFs on iPhone and iPad.  

Similar to Preview on Mac, iOS has a built-in Markup feature that lets you sign PDFs in the Files or Mail app. 

Here’s how to sign a PDF on iPhone and iPad:  

1. Open your PDF in Files or Mail.
2. Click the Markup icon that looks like a pencil.
3. Click the plus button in the bottom right corner > Signature.
4. Draw your signature and click Done. 

The signature will be added to your PDF. You can move it around on the page or reuse it in the future — just open the Signature menu in a different document and select it from there.

If you are using Nitro PDF Pro, the process is as follows.

1. Open Nitro PDF Pro and open a document.
2. At the top of the screen, click Edit (the pencil icon).
3. At the bottom of the screen, in the center, click the arrow icon.
4. Scroll down and select Stamps > Sign. This adds a stamp to your document indicating where to sign. 

5. Tap the same arrow icon in the bottom center again and choose Scribble. 
6. Draw your signature on the document.

If you want to make the process more secure, use Nitro Sign (free for 14 days).

Go to Nitro Sign, download and open the document you need. There, you can add your own signature and then invite another person to sign it via email. Once the recipient reviews or signs the document, the information will appear in your personal account. The recipient doesn't need to have Nitro Sign to sign your document.

Tip: To further optimize your document workflows, try the free Productivity Tools Finder

Best tools to sign PDF on Mac and iPhone for free

As you can see, you can learn how to electronically sign PDF on a Mac and iPhone using the tools built into your computer. However, there's a much larger PDF world out there that is specifically designed to make your workflow as efficient as possible. For PDF signing and editing, I highly recommend Nitro PDF Pro, which can easily become your go-to tool for all PDF tasks. 

Nitro PDF Pro, as well as the other apps mentioned here, are available to you absolutely free with a seven-day trial of Setapp, a platform of more than 260 useful macOS and iOS apps for every task. Try them for free today!