Many forms still come as a PDF with a line that says sign here. Adobe Acrobat can do it, but it is a heavy install and a subscription for a one-minute job. There are lighter ways, and which one is best depends on the device you are holding.
Two kinds of signature
Before choosing a method, know what you are adding. An image signature is a picture of your handwriting placed on the page, the digital equivalent of signing a printout. A certificate-based digital signature ties the document to an identity cryptographically and shows a validity panel in PDF readers. The methods below add an image signature, which is what permission slips, rental forms, internal paperwork and delivery notes usually expect. If a contract or a filing asks for more, check what they accept before you sign.
On a Mac: Preview
Preview is built into macOS and can sign without any other software.
- Open the PDF in Preview and click the Markup toolbar button.
- Click the signature button. You can create a signature with the trackpad, with the camera by signing on white paper, or on an iPhone nearby.
- Click your saved signature to place it, then drag and resize it onto the line.
- Choose File, then Save.
On an iPhone or iPad: Markup
The Files app can mark up PDFs directly.
- Open the PDF in Files and tap the markup icon.
- Tap the plus button and choose Signature, then draw one with your finger.
- Drag the signature onto the line, resize it, and tap Done.
In any browser: Sign PDF
If you are on Windows, Android, a Chromebook or a shared computer, a browser tool is the simplest option.
- Open Sign PDF and choose your PDF.
- Create a signature by drawing it, typing your name in a script style, or uploading a photo of your handwriting.
- Drag it onto the right page and line, and adjust the size.
- Save the signed copy. The original is not changed.
The PDF is processed in your browser and is not uploaded. Sign PDF is a DocPro Pro tool on the web, A$5.99/month after a 7-day free trial. You can open it and set up your file without an account, and the final save asks you to sign in. With the Signature vault you can keep your signature and initials on your own device, ready to reuse.
Print, sign and scan
It still works, and it is the fallback when nothing else is available. Print the page, sign with a dark pen, and scan or photograph it flat in even light. Then turn the photos into a PDF with JPG to PDF. The cost is paper, time and a file that is often large, so you may need to compress it afterwards.
Tips for a clean result
- Use a dark pen on white paper when you make a signature image, and crop close so there is no grey border.
- Keep a transparent or white background so the signature does not hide the line it sits on.
- Flatten the file afterwards if it has form fields and you do not want them edited. Flatten PDF locks the content in place.
- Add a password if the signed file goes by email and contains personal details. Protect PDF adds AES-256 encryption.
Which method should you pick?
- You own a Mac or iPhone and sign occasionally: use Preview or Markup. They are free and already installed.
- You use Windows or Android, or sign often: a browser tool saves time, especially if you keep a saved signature.
- The document needs a witness or a wet ink signature: print, sign and scan, as the rules require.
- The document needs legal-grade proof of identity: use an e-signature service or a certificate-based signature, as the other party specifies.
Keep your signature safe
A signature image is easy to copy. Do not post a clean image of it online, do not send it in plain emails when a form does not need it, and keep the file on your own device. If you share a signed PDF widely, consider adding a note next to the signature such as the date and purpose, so the image cannot easily be reused on another document.
For a phone-focused walk-through, see How to sign a PDF on your phone.
Frequently asked questions
Is a signature image legally valid?
It depends on the document and the country. For many everyday forms an image of your signature is accepted, but contracts, government filings and some regulated work may need a certificate-based digital signature or a specific e-signature service. Ask the other side what they accept.
Can I sign a PDF for free?
Yes, with the built-in tools on a Mac or iPhone, or by printing and scanning. DocPro's Sign PDF is a paid Pro tool, with a 7-day free trial.
Will the signed PDF still be editable?
The signature is placed on the page. If you want to stop others changing the form fields afterwards, flatten the PDF so the content becomes fixed.