The fastest way depends on what you already have

You can digitally sign a PDF using built-in tools on your computer, free online services, or paid software — and the right choice depends on whether you need a legally binding signature or just a way to show you approved the document. Most people can sign a PDF in under five minutes using free tools that came with their operating system or a web browser.

If you have Adobe Acrobat Reader (the free version), you can sign directly in the app. On Windows or Mac, you can also use Preview on Mac or Microsoft Edge on either system. If you do not have any of these, free online services like DocuSign, HelloSign, or Smallpdf let you upload a PDF, draw or type your signature, and download the signed copy — no account required for a single document.

Key Takeaways

  • Adobe Acrobat Reader's free version includes a "Fill & Sign" tool that lets you sign PDFs without paying for the full Acrobat subscription.
  • Mac users can open any PDF in Preview, use the Markup toolbar to add a signature, and save the file without installing anything extra.
  • Windows users can open PDFs in Microsoft Edge and use the built-in annotation tools to sign and save the document.
  • Free online services like Smallpdf or DocuSign work on any device with a web browser and do not require you to install software.
  • A digital signature drawn or typed into a PDF is not legally binding in most cases — you need a certified digital certificate for contracts or official documents.

Signing a PDF in Adobe Acrobat Reader (Windows and Mac)

Open the PDF in Adobe Acrobat Reader, then click the Fill & Sign tool in the right panel. If you do not see it, click the Tools icon (three horizontal lines) at the top right and select Fill & Sign from the menu. The tool is free even though the full Acrobat subscription costs money.

Click the signature icon in the toolbar at the top, then choose whether to draw your signature with your mouse or trackpad, type your name, or upload an image of your handwritten signature. Once you have created your signature, click where you want it to appear on the PDF. You can resize and reposition it before saving. When you are done, go to File > Save to keep the signed version.

Signing a PDF on Mac using Preview

Open the PDF in Preview (the default PDF viewer on Mac), then click the Markup toolbar icon — it looks like a pen in a circle and sits in the top right corner. If you do not see it, go to Tools > Annotate > Show Markup Toolbar.

Click the signature icon in the Markup toolbar (it looks like a cursive line), then choose to create a new signature by drawing it, typing it, or scanning it from a trackpad gesture. Once your signature is created, click on the PDF where you want it to appear. You can adjust the size by dragging the corners. Save the file using File > Save or Command+S.

Signing a PDF on Windows using Microsoft Edge

Open the PDF in Microsoft Edge, then click the Draw tool in the toolbar at the top right (it looks like a pen). Select a pen color and thickness if you want to customize the appearance.

Draw your signature directly on the PDF, or use the eraser tool to fix mistakes. Once you are satisfied, click the Save button in the top right corner. Edge will save the PDF with your signature included. If you prefer to type your name instead of drawing, you can use the text tool before saving.

Signing a PDF online without installing software

Go to Smallpdf.com, DocuSign.com, or HelloSign.com and look for the "Sign PDF" or similar option on the homepage. Upload your PDF file, then draw, type, or upload an image of your signature. These services let you place your signature anywhere on the document and resize it as needed.

After signing, download the completed PDF to your computer. Most of these services do not require you to create an account for a single document, though signing up lets you save templates and sign multiple documents faster. The free versions work for personal and business use, though some have limits on how many documents you can sign per month.

The difference between a drawn signature and a certified digital signature

A signature you draw, type, or upload into a PDF is not legally binding in most situations. It shows that you opened and marked the document, but it does not prove you signed it or that the document has not been changed since you signed it. For contracts, legal agreements, or official paperwork, you need a certified digital signature backed by a digital certificate from a trusted authority.

Certified digital signatures use encryption to prove the signer's identity and detect any changes to the document after signing. Services like DocuSign, Adobe Sign (the paid version), and specialized legal platforms offer certified signatures, though they usually cost money and require you to verify your identity. For everyday documents like approving a draft or confirming you have read something, a drawn or typed signature is enough.

Signing multiple PDFs or the same PDF repeatedly

If you sign the same document often, save your signature as a reusable image. In Adobe Acrobat Reader, once you create a signature, it stays in your signature list and you can apply it to any future PDF without redrawing it. On Mac Preview, your signature is saved automatically after you create it the first time.

For signing many different documents, online services like DocuSign and HelloSign let you upload your signature once and then apply it to multiple PDFs in one session. Some also let you set up templates so that signature fields appear in the same place every time, which speeds up the process if you sign similar documents regularly.

Frequently Asked Questions

Can someone else sign a PDF I send them?

Yes. Send them the unsigned PDF file, and they can open it in any of these tools and add their own signature. If you need multiple people to sign the same document in order, services like DocuSign and HelloSign let you set up a signing order so each person signs after the previous one finishes.

What if I want to sign a PDF on my phone?

Adobe Acrobat Reader has a mobile app for iPhone and Android with a Fill & Sign tool. You can also use free online services like Smallpdf or DocuSign through your phone's web browser. Some phones also let you take a photo of your handwritten signature and insert it into a PDF.

Does signing a PDF change the original file?

No. When you save a signed PDF, you are creating a new file with your signature added. The original unsigned PDF remains unchanged. Most tools let you choose where to save the signed version so you can keep both copies.

Is a typed name as valid as a drawn signature?

For everyday purposes, yes — a typed name, a drawn signature, and an uploaded image all work the same way in a PDF. For legal documents, none of them are valid without a certified digital certificate. The type of signature does not matter; the certification does.

Can I sign a PDF that is password-protected?

Not usually. If a PDF is locked or restricted, you will need the password to open it before you can sign it. Ask whoever sent you the document for the password, or contact them to send you an unlocked version.