How to sign a PDF on Mac, iPhone, and iPad [2024]

It takes me just about 20 seconds to sign any PDF. Over the last two years, all of my contracts, cooperation agreements, service agreements, etc., have been signed digitally in PDF format. [And I sincerely hope I never have to go back to the crazy print-sign-scan-send-back manual routine again.]

During this time, I’ve discovered some great ways how to digitally sign a PDF and encountered a few methods to avoid. So, let me share how to create a digital signature and how to insert signatures into PDFs.

How to sign a PDF securely

MacBooks have a built-in way to sign documents through Preview. I'll discuss this method later because there're two concerns about it. 

First, the built-in method involves adding and saving your signature in the PDF Mac Markup menu. The purpose is to let you reuse them in the future, but this could create a major vulnerability since Preview is the first place that someone looking to gain access to your signatures will check.  

Second, the Markup tool won’t help you make some major edits in a PDF. 

That's why I'd like to start with the recommendation of Nitro PDF Pro – a full-featured, pro-level PDF editing app that fixes both problems. After you install it, 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. It's a tool that 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, which can be purchased here. A 14-day trial period is available.

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.

Digitally sign a PDF in Preview

You might be surprised to know that there’s free PDF signature functionality already on your Mac. In fact, the default app you use to open images, Preview, is able to sign PDFs. (However, keep in mind the caveats mentioned above.)

Here's how to digitally sign a PDF in Preview.

1. Open any document that requires a signature with Preview.
2. Open the Markup menu (click the icon with the pencil in a circle in the upper right corner).
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 using 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.

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 camera

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.

How to sign PDFs in Mail and send them via email

Here's how to sign a PDF 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 signature in PDF

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 secured place. Here's how.

1. Create a signature in a drawing app. In this example, I'm using Tayasui Sketches, which is similar to Paint for Mac. But you could just as easily 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 Mac.

Signing a PDF on iPhone and iPad

Now that you know how to sign documents on 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.  

Similarly 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 use it:  

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.

Try all the best tools to sign PDF 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 250 useful macOS and iOS apps for every task. Try them for free today!

FAQs

What are the benefits of digital signature in PDF? 

First, speed. You receive a document by email, sign it, and send it to the next recipient. Second, security. Special tools like Nitro Sign (from Nitro PDF Pro ) allow you to grant signature access only to a specific email address and track the process of viewing and signing the file.

What is the best tool for signing PDF files?

I prefer Nitro PDF Pro, which is my go-to PDF editor. The built-in Preview also has signature capabilities, but Nitro PDF Pro is a more complete and advanced editor overall, so I just use its features. 

Can you digitally sign a fillable PDF?

Yes, you can. First, fill out all the forms and make sure the information is correct, then apply a digital signature. Depending on the tool you are using, you will usually need to select the Sign option, Add Signature, or something similar. 

Why PDF editor is the best choice for digital signatures?

PDF has become one of the most important formats for document exchange because it is compatible with all major operating systems and platforms. On any of them, the files are displayed exactly as they were created, without any changes in text formatting. As a result, many signature tools have been developed for PDF, including highly secure ones, and many people prefer to sign electronic documents in PDF format.