How to Add a Signature to a PDF for Free
To add a signature to a PDF for free, open it in an app that has a signing tool: Markup in the iPhone Files app, the Sign button in Mac Preview, or Fill & Sign in the free Adobe Acrobat Reader on Windows and Android. Draw or type your signature once, place it on the signature line, resize it and save the PDF. You can also add a photo of your real signature as a transparent PNG.
The quickest way on each device
| Device | Free app | Where to find it |
|---|---|---|
| iPhone or iPad | Files (Markup) | Pen button > + > Add Signature |
| Mac | Preview | Markup toolbar > Sign |
| Windows | Adobe Acrobat Reader | Fill & Sign > Sign |
| Android | Adobe Acrobat Reader app | Fill & Sign > Create signature |
Sign a PDF on iPhone or iPad
- Save the PDF to the Files app (from Mail, tap the attachment, then the Share button and Save to Files).
- Open the PDF in Files and tap the Markup (pen) button.
- Tap + and choose Add Signature. Sign with your finger, then tap Done. The iPhone remembers the signature for next time.
- Drag the signature onto the line and use the corners to resize it.
- Tap Done. The signed PDF replaces the original in Files, ready to share.
Sign a PDF on a Mac
- Open the PDF in Preview.
- Click the Show Markup Toolbar button (a pen tip in a circle), then the Sign button.
- Create a signature: draw it on the trackpad, hold a signature written on white paper up to the camera, or use your iPhone.
- Click the signature to place it, then drag and resize it on the line.
- Choose File > Save, or File > Export as PDF to keep the unsigned original.
Sign a PDF on Windows
Windows has no built-in PDF signing tool, but the free Adobe Acrobat Reader does it well:
- Open the PDF in Acrobat Reader and choose Fill & Sign (under All tools in newer versions).
- Choose Sign, then Add signature.
- Type your name in a handwriting style, draw with the mouse, or upload an image of your signature, then click Apply.
- Click where the signature should go, resize it and save the PDF.
Without Acrobat Reader, you can open the PDF in Microsoft Edge, choose Draw and sign with the mouse or a pen, then save. It works, but a mouse signature rarely looks neat.
Sign a PDF on Android
Install the free Adobe Acrobat Reader app, open the PDF, tap the edit button, choose Fill & Sign, create a signature with your finger and tap to place it.
Use a photo of your real signature
A signature drawn with a finger or a mouse often looks shaky. For a cleaner result, sign on white paper and turn it into an image you can reuse:
- Sign with a dark pen on plain white paper and take a sharp photo from directly above, in daylight.
- Open the Background Remover, choose the photo and keep Transparent selected. The paper disappears and only the ink remains.
- Download the PNG. If a form needs a small file, shrink it with the Image Resizer in KB.
- Add the PNG with the image option in Acrobat Reader's Fill & Sign, or paste it onto the page in Preview.
Both tools run in your browser, so the image of your signature is never uploaded. Still, keep the PNG in a private folder and do not post it online.
Electronic vs digital signatures
- Electronic signature: an image of your signature, or your typed name, placed on the PDF. This is what the methods above create, and it is what most job, rental, school and business forms need.
- Digital signature: a certificate-based signature (for example from Acrobat's Use a certificate option or an official ID) that locks the document and proves who signed it. Use one when the sender asks for it specifically.
Before you send the signed PDF
- Zoom in to check the signature sits on the line and is not covering any text.
- Keep an unsigned copy in case you need to correct something.
- If you have several signed pages, join them into one file with Merge PDF; if the file is too large for email, shrink it with Compress PDF.
Frequently asked questions
Is an electronic signature on a PDF legally valid?
For most everyday documents, yes. In the US the ESIGN Act and UETA, and in the UK the Electronic Communications Act 2000, accept electronic signatures for most contracts. Some documents, such as wills and certain property deeds, still need a handwritten signature, so check with whoever asked you to sign.
What is the difference between an electronic and a digital signature?
An electronic signature is your signature drawn, typed or pasted onto the document. A digital signature is a certificate-based signature that also proves the PDF has not been changed since it was signed. Most forms only need an electronic signature; a digital signature is used when the sender asks for one.
How do I sign a PDF on iPhone?
Open the PDF in the Files app, tap the Markup (pen) button, tap +, choose Add Signature and draw your signature. Drag it onto the signature line, resize it and tap Done.
How do I sign a PDF someone sent through DocuSign?
Open the link in the email, review the document and follow the yellow Sign tags. You do not need a DocuSign account to sign a document sent to you; an account is only needed to send documents for signing.
How do I edit a PDF after it was signed?
If it has an electronic signature added in Preview or Markup, you can usually still edit it. If it has a certificate-based digital signature, any change breaks the signature, so ask the sender for the unsigned version, make the change and sign it again.
How do I fill out a PDF form before signing?
Open the form in Acrobat Reader, Preview or a web browser and click into the boxes to type. If the PDF has no form fields, use Fill & Sign in Acrobat Reader or the text tool in Preview to place text anywhere on the page.