The fastest way: use Preview, which is already on your Mac

macOS comes with a built-in tool called Preview that can add your signature to a PDF without downloading anything else. Open the PDF in Preview, click the Markup toolbar button (it looks like a toolbox), select Signature, and choose or create your signature. Then click where you want it on the page. The signature appears as an image, not as a legally binding digital signature — but for most everyday documents like rental agreements, permission forms, or contracts between people you know, this is what you actually need.

If you have never created a signature in Preview before, you will need to do that first. Open any PDF, click Markup, then Signature, then Create Signature. You can draw one with your trackpad or take a photo of your handwritten signature with your Mac's camera. Save it, and it stays available for future PDFs.

Key Takeaways

  • Preview, built into every Mac, can add a handwritten-style signature to any PDF without installing software.
  • Your signature in Preview is a visual image, not a cryptographic digital signature — sufficient for most personal and business documents.
  • You can draw your signature with the trackpad or photograph a handwritten one, and Preview remembers it for future use.
  • For legally binding signatures on contracts that require proof of identity or tamper-detection, you will need a third-party service like DocuSign or Adobe Sign.

Creating and storing your signature in Preview

The first time you sign a PDF in Preview, you create a signature and store it on your Mac. Open Preview, go to Tools menu, click Signature, then Create Signature. You will see two options: Trackpad or Camera.

Trackpad means you draw your signature on the trackpad with your finger or trackpad stylus. It captures the motion and produces a signature that looks handwritten. Camera means you write your signature on paper, hold it up to your Mac's camera, and Preview photographs it. Both methods work; choose whichever feels more natural. Once you create a signature, Preview saves it and shows it as an option every time you open the Signature menu in any PDF.

If you want to delete a saved signature or create a new one, return to Tools > Signature and you will see your existing signatures listed. Click the one you want to remove and press Delete, or create a new one by clicking Create Signature again.

Adding your signature to a specific PDF

Open the PDF you want to sign in Preview. Click the Markup toolbar button — it looks like a toolbox and sits in the top right of the Preview window. If you do not see it, go to Tools menu and select Annotate.

In the Markup menu, click Signature, then select the signature you want to use. Your cursor will change. Click the spot on the PDF where you want the signature to appear. The signature will be placed there as an image. You can click and drag it to move it, or click and drag the corner handles to resize it.

Once you are satisfied, save the PDF. Use File > Save or press Command+S. Preview will ask whether you want to save changes to the original file or create a new one. Choose based on whether you want to keep an unsigned copy — many people save the signed version with a new name like "contract_signed.pdf" to preserve the original.

When Preview is not enough: legally binding signatures

Preview signatures work for most everyday situations: leases, permission slips, internal company forms, or any document where both parties trust each other and do not need proof that the signer is who they claim to be. The signature is just an image embedded in the PDF, so it proves nothing about identity or whether the document was altered after signing.

If you need a legally binding digital signature — one that proves who signed it and detects tampering — you need a third-party service. DocuSign, Adobe Sign, and HelloSign all offer this. These services use cryptographic signatures that are tied to your identity and create an audit trail showing when and where the document was signed. They cost money, usually per signature or per month, but they are the standard for contracts, financial documents, and anything that might end up in court.

Your bank, insurance company, or law firm will usually tell you which service they use if they require a legally binding signature. Do not assume Preview is sufficient for those situations — ask first.

Troubleshooting common problems

If the Markup button does not appear in Preview, make sure you have the latest version of macOS. Go to Apple menu > System Settings > General > Software Update and install any available updates. Markup has been standard in Preview since macOS 10.12 (Sierra), released in 2016, so if your Mac is older than that, you may need to update.

If you created a signature but it does not appear in the Signature menu, the signature may not have saved properly. Try creating it again. Draw or photograph it more slowly and deliberately — Preview sometimes misses quick or faint strokes. If the problem persists, restart Preview and try again.

If you want to sign a PDF but cannot open it in Preview, try dragging the PDF directly onto the Preview icon in your Applications folder, or right-click the PDF and select Open With > Preview. Some PDFs are locked or encrypted and cannot be edited in Preview; in that case, you will need to contact whoever sent you the PDF and ask for an unlocked version, or use a third-party service.

Saving and sharing your signed PDF

After you sign a PDF in Preview and save it, the file is ready to send. Email it, upload it to a shared folder, or deliver it however the other party requested. The signature is now part of the PDF file itself, so it will appear the same way on anyone else's computer or phone.

If you need to send the PDF to multiple people or collect signatures from multiple signers, Preview is not the right tool — each person would need to open the file, add their own signature, and send it back. For workflows where multiple people sign the same document in sequence, DocuSign or Adobe Sign handle the routing automatically and are worth the cost.

Frequently Asked Questions

Is a Preview signature legally valid?

A Preview signature is legally valid for most everyday documents between people who trust each other. It proves you signed it, but not who you are or whether the document was changed after signing. For contracts, financial documents, or anything that might be disputed, ask the other party whether they need a cryptographically signed version from DocuSign or Adobe Sign instead.

Can I use the same signature on every PDF?

Yes. Once you create a signature in Preview, it stays saved on your Mac and appears in the Signature menu for every PDF you open. You can create multiple signatures if you want different ones for different purposes — a formal one for business, a casual one for personal documents.

What if I make a mistake and sign the wrong spot?

Undo the signature by pressing Command+Z before you save the file. If you have already saved, open the file again, undo, and save again. Preview will ask whether you want to save changes to the original or create a new file.

Can I sign a PDF on my iPhone and use that signature on my Mac?

Not directly. Signatures created on iPhone are stored separately from your Mac. The easiest approach is to create your signature once in Preview on your Mac, then use it on any Mac you own. If you want to sign PDFs on your iPhone, use the built-in Notes app or a third-party service like DocuSign that syncs across devices.

Does Preview work with fillable PDF forms?

Preview can add a signature to any PDF, including fillable forms. Open the form, fill in the text fields if you can, then add your signature using Markup. Some forms are locked and do not allow editing in Preview; if that happens, try opening the form in Adobe Reader or ask whoever created the form for an unlocked version.