The fastest way to sign a PDF depends on what you already have

You can sign a PDF three ways: draw your signature on screen, upload an image of your handwritten signature, or use a typed text version. The method you choose depends on whether you're signing alone or sending the document to others, and whether you need the signature to be legally binding.

Most PDF readers built into your computer or phone can add a basic signature without extra software. If you need a legally recognized signature — one that proves you signed it and that nobody changed it afterward — you'll need a tool that creates what's called a digital signature, which is different from just drawing your name on the page.

Key Takeaways

  • Adobe Acrobat Reader (the free version) lets you draw, type, or upload a signature image, but the signature is not legally binding.
  • Adobe Acrobat Pro, Preview on Mac, and some free tools like Sejda can add signatures that look professional but still aren't legally binding.
  • A legally binding digital signature requires a certificate from a trusted authority and software that supports it, like Adobe Acrobat Pro with DocuSign or Adobe Sign.
  • For most everyday signing — contracts, forms, permission slips — a drawn or typed signature in a free tool is enough.
  • The signature stays in the PDF and moves with it, so the recipient sees it when they open the file.

Signing with Adobe Acrobat Reader (free)

Open your PDF in Adobe Acrobat Reader, the free version. Click the Fill & Sign tool in the right panel, or look for a pencil icon. Choose Sign from the menu that appears.

You have three options: draw your signature with your mouse or trackpad, type your name in a signature font, or click Image to upload a photo of your handwritten signature. Once you place it on the page, you can resize and move it. Click Apply when you're done.

Save the file. The signature is now part of the PDF and will appear when anyone opens it. This method works on Windows, Mac, and mobile devices, but the signature is not legally binding — it's just an image or text placed on the page, and there's no way to prove you created it or that the document hasn't been changed since you signed.

Signing with Preview on Mac

If you use a Mac, Preview (the built-in image viewer) can sign PDFs without downloading anything else. Open the PDF in Preview, then click Tools in the menu bar and select Annotate. Click the signature icon (it looks like a pen) in the toolbar.

The first time you sign, Preview will ask you to create a signature. You can draw it with your trackpad, use your iPhone or iPad camera to photograph your handwritten signature, or type your name. Once created, your signature is saved and you can use it on any PDF you open in Preview.

Click where you want the signature to appear on the page, then save the file. Like Acrobat Reader, this creates a visual signature but not a legally binding one.

Signing with free online tools

Sejda, iLovePDF, and SmallPDF all let you upload a PDF and add a signature without installing software. Go to the tool's website, click the option to sign or annotate, and upload your PDF. Draw, type, or upload an image of your signature, place it on the page, and download the signed file.

These tools work on any device with a web browser. The downside is that you're uploading your document to someone else's server, which matters if the PDF contains sensitive information. Most of these services say they delete files after a few hours, but read their privacy policy first.

Like the desktop options above, these create a visual signature, not a legally binding digital signature.

Creating a legally binding digital signature

A digital signature is cryptographically tied to you and the document. It proves you signed it, and it breaks if anyone changes the PDF afterward. Most everyday signing doesn't need this level of security, but contracts, financial documents, and official filings sometimes do.

To create a legally binding digital signature, you need a certificate from a trusted authority (called a Certificate Authority). Adobe Acrobat Pro can create and manage these signatures. You'll also need software that supports digital signatures — Adobe Sign, DocuSign, and HelloSign all do this, but they charge a monthly fee or per-signature cost.

The process is more complex: you obtain a certificate (which costs money and requires identity verification), install it on your computer, then use Acrobat Pro or another certified tool to sign. The recipient can verify that the signature is genuine and that the document hasn't been altered.

Sending a PDF for others to sign

If you need someone else to sign the PDF, the easiest route depends on how many people need to sign and whether you need legally binding signatures.

For a single person or a small group, use Adobe Sign (part of Adobe Acrobat Pro subscription), DocuSign, or HelloSign. Upload your PDF, mark where signatures should go, enter the signer's email address, and send. The recipient gets a link, signs on their device, and the signed PDF comes back to you. These services create signatures that are legally binding in most jurisdictions.

For informal signing — a permission slip, a casual agreement — you can email the PDF and ask the person to sign it using any of the free methods above (Acrobat Reader, Preview, or an online tool) and send it back.

Where the signature appears and how to move it

When you add a signature, it appears as a box on the page. Click and drag to move it, or grab the corner handles to resize it. The signature stays in that exact spot when you save the file.

If you need to sign multiple pages, you'll add the signature to each page separately. Some tools (like Adobe Sign) let you mark all the signature locations at once, then sign them all in one action.

Once you save, the signature is permanent. You can't remove it without using a tool that edits PDFs, like Adobe Acrobat Pro or Preview. If you make a mistake, you'll need to start over with a fresh copy of the unsigned PDF.

Frequently Asked Questions

Can I sign a PDF on my phone?

Yes. Adobe Acrobat Reader, Preview (on iPad), and most online signing tools work on phones and tablets. Open the PDF, tap the signature tool, draw or type your name, and save. The process is the same as on a computer.

Is a signature I draw in Acrobat Reader legally binding?

No. A drawn or typed signature in Acrobat Reader, Preview, or free online tools is just an image placed on the page. It's not legally binding because there's no way to prove you created it or that the document hasn't been changed. For legally binding signatures, you need a digital certificate and software that supports it, like Adobe Sign or DocuSign.

What's the difference between a signature and a digital signature?

A signature is a visual mark — your name written or drawn on the page. A digital signature is cryptographically linked to you and the document. It proves you signed it and breaks if anyone changes the PDF. Digital signatures require a certificate and specialized software.

Can I reuse the same signature on multiple PDFs?

Yes. Most tools save your signature after you create it the first time. In Adobe Acrobat Reader and Preview, your signature is stored and you can apply it to any PDF. Online tools usually ask you to create or upload it each time, though some let you save it to your account.

What happens if I sign a PDF and then change it?

If you use a visual signature (drawn, typed, or uploaded), the PDF can be edited after signing and there's no way to tell. If you use a legally binding digital signature, the signature becomes invalid if anyone changes the document — the recipient will see a warning that the PDF has been altered.