The two ways to sign a PDF: software tools and built-in readers
You can add your signature to a PDF in two main ways. The first is using your computer's PDF reader — Adobe Acrobat Reader, Preview on Mac, or Windows built-in PDF viewer — which all have a signature tool built in. The second is using dedicated software like Adobe Acrobat Pro, DocuSign, or HelloSign, which offer more control over where your signature appears and how it looks. For most people signing a single document, the free reader method works fine. If you sign documents regularly or need to send them to others for signing, dedicated software saves time.
The difference matters because free readers let you sign and save, but they do not always let you send the signed document directly to someone else or add multiple signatures to the same file. Paid software handles those tasks automatically. Your choice depends on whether you are signing something for yourself or managing signatures from multiple people.
Key Takeaways
- Adobe Acrobat Reader, Preview, and Windows PDF viewer all have free signature tools built in — you do not need to buy software to sign a single document.
- To sign in your free reader, open the PDF, find the signature tool, draw or type your signature, and place it on the page where you want it.
- If you sign documents regularly or need others to sign them, dedicated tools like DocuSign or Adobe Acrobat Pro automate the process and track who signed what.
- Your signature in a PDF reader is a visual mark only — it does not create a legally binding digital signature unless you use software that adds encryption.
Signing a PDF with Adobe Acrobat Reader on Windows or Mac
Open the PDF in Adobe Acrobat Reader. Click the Fill & Sign tool in the right panel, or go to Tools menu and select Fill & Sign. Click the signature icon (it looks like a pen) in the toolbar that appears. A dialog box will open asking you to create your signature. You can type your name, draw it with your mouse or trackpad, or upload an image of your handwritten signature.
Once you have created your signature, click explore. Your cursor will change to a crosshair. Click and drag on the PDF page where you want your signature to appear. You can resize it by dragging the corners. When you are satisfied, save the file using File > Save or Ctrl+S (Windows) or Command+S (Mac). The signature is now part of the PDF.
If you need to sign the same document multiple times or add initials in a different location, repeat the process. You can also delete a signature by clicking it and pressing Delete, then place a new one elsewhere on the page.
Signing a PDF with Preview on Mac
Open the PDF in Preview (the default PDF viewer on Mac). Click the Markup Toolbar button in the top right — it looks like a toolbox. Click the signature icon in the toolbar that appears. If you have not created a signature in Preview before, you will see a dialog asking you to create one. You can draw your signature using your trackpad, use your Mac's camera to photograph a handwritten signature, or type your name.
After creating your signature, click Done. Your signature will appear on the PDF. Click and drag it to position it where you want it on the page. You can resize it by dragging the corner handles. Save the file using File > Save or Command+S. Your signature is now embedded in the PDF.
Signing a PDF with Windows built-in PDF viewer
Open the PDF in Microsoft Edge or the Windows Photos app (both have PDF viewing built in). In Edge, click the Draw tool in the top toolbar. A drawing panel will open on the right side. Select a pen tool and color, then draw your signature directly on the PDF. You can also use the text tool to type your name if you prefer.
Once your signature is in place, save the file using File > Save or Ctrl+S. The signature becomes part of the PDF. If you make a mistake, use the eraser tool to remove it and try again. This method is simpler than Adobe Reader but gives you less control over signature appearance — you are essentially drawing on the document rather than placing a pre-made signature.
Using DocuSign or Adobe Acrobat Pro for regular signing
If you sign documents regularly or need to send documents to others for signing, dedicated software is faster. DocuSign and Adobe Acrobat Pro both let you upload a PDF, place signature fields where they need to go, and send the document to other people. They track who has signed, when they signed, and what the signature looks like. The software also adds encryption that makes the signature legally binding in most jurisdictions.
DocuSign is free for up to three documents per month. You upload the PDF, click where you want signatures to appear, add the email addresses of people who need to sign, and send. Each person receives a link, signs on their own device, and the completed document comes back to you automatically. Adobe Acrobat Pro costs money but integrates with your existing Adobe tools and works offline. Both services keep a record of every signature for legal purposes.
Where to place your signature on a PDF
Signature placement depends on the document type. On contracts, your signature usually goes at the bottom right of the last page, above your printed name. On forms, there is usually a blank line marked "Signature" — place your signature there. On letters, sign below your typed name at the end. If the PDF has signature fields already marked (they often appear as gray boxes), click inside the box and your signature will be placed there automatically.
If you are unsure where to sign, look for a line, box, or the word "Signature" on the document. If none exists, the bottom right of the last page is the standard location. You can always move your signature after placing it by clicking and dragging it to a new spot.
The difference between a visual signature and a digital signature
When you sign a PDF using a free reader, you are adding a visual signature — an image of your name or handwriting that appears on the page. This is legally acceptable for most documents, but it does not prove who signed it or when. Anyone with the PDF can copy your signature and paste it on another document.
A digital signature created by DocuSign, Adobe Acrobat Pro, or similar software includes encryption and metadata. It proves who signed the document, when they signed it, and whether the document has been changed since signing. Digital signatures are required for legal contracts, financial documents, and government filings in most places. For casual documents like permission slips or personal letters, a visual signature is fine. For anything legally important, use software that creates a digital signature.
Frequently Asked Questions
Can I sign a PDF on my phone or tablet?
Yes. Adobe Acrobat Reader, DocuSign, and HelloSign all have mobile apps. Open the PDF in the app, tap the signature tool, draw or type your signature, and save. The process is the same as on a computer, though drawing a signature with your finger is less precise than using a mouse or trackpad.
What if the PDF is locked and I cannot edit it?
Some PDFs have editing restrictions to prevent changes. Try opening it in Adobe Acrobat Pro instead of the free reader — Pro can sometimes unlock restricted PDFs. If that does not work, ask the person who sent you the PDF to remove the restriction and send it again. You cannot legally remove restrictions yourself.
Does my signature in a PDF hold up in court?
A visual signature (drawn or typed in a free reader) is usually accepted as proof you signed the document, but it does not prove when you signed it or that the document has not been changed. A digital signature from DocuSign or Acrobat Pro includes that proof and is stronger evidence in court. For important legal documents, use a service that creates a digital signature.
Can I reuse the same signature on multiple PDFs?
Yes. Once you create a signature in Adobe Reader, Preview, or another tool, it is saved. The next time you sign a PDF, your saved signature appears automatically. You can also create multiple signature styles and choose which one to use each time.
What happens if I sign a PDF and then the document changes?
If you added a visual signature with a free reader, the document can be edited after you sign it and you will not know. If you used DocuSign or Acrobat Pro to create a digital signature, the software will flag the document as tampered with if anyone tries to change it after signing. This is why digital signatures matter for important documents.