You can sign a PDF without paying for software or ending up with a watermark, on Windows, Mac, and iPhone. The tools are already on your device. This guide covers exactly how to place your mark, explains the gap between an electronic and a digital signature, and gets the file ready to send. The main search phrase here is sign pdf free. Every method costs nothing.

Sign a PDF on Windows with Adobe Acrobat Reader

Windows users get a capable free option in Adobe Acrobat Reader. Its Fill & Sign tool lets you place a mark three ways.

  1. Open the PDF in Adobe Acrobat Reader.
  2. Click the Fill & Sign tool in the right panel.
  3. Select Sign Yourself, then choose Type, Draw, or Image.
  4. If you choose Draw, use your mouse or touchscreen to create the mark.
  5. If you choose Image, upload a picture of your handwritten name (a photo of a signed paper works).
  6. Place the mark on the document where needed and save the file.

No subscription is required. What you add is an electronic mark, not a certificate-based digital signature.

Sign a PDF on Mac with Preview

Mac users can sign a PDF without buying anything. The built-in Preview app has a Markup toolbar with a Sign feature. Here is the procedure:

  1. Open the PDF in Preview.
  2. Click the Markup toolbar icon (a pen tip) or go to View > Show Markup Toolbar.
  3. Click the Sign button.
  4. Choose Create Signature. Draw with the trackpad, or hold a signed piece of paper up to the camera so Preview captures it.
  5. Preview saves the mark. Click it to place it on the PDF.
  6. Drag and resize as needed, then save the file.

Capture a handwritten mark with the camera

Hold a signed paper in front of your Mac's camera. Preview detects the mark and lets you add it straight to the PDF. It is the fastest way to reuse an existing pen-and-ink version without a scanner.

Using Preview to sign a PDF on Mac is entirely free and requires no extra downloads.

Sign a PDF on an IPhone with the Files App

On an iPhone, the built-in Files app handles signing. No third-party apps needed. Follow these steps:

  1. Open the PDF in the Files app.
  2. Tap the Markup icon (a pen tip) at the top of the screen.
  3. Tap the + button, then choose Add Signature.
  4. Draw your mark with a finger or a stylus.
  5. Tap Done, then place the mark on the document.
  6. Tap Save.

This works on any recent iPhone and costs nothing. The result is an electronic image of your name.

Electronic vs Digital Signature What is the Difference?

When you place a mark using the methods above, you are creating an electronic signature. It is an image, a typed name, or a drawn mark that represents your intent to sign. No encryption. No certificate.

A digital signature is different. It uses a certificate issued by a trusted authority to lock the document. If anyone changes the PDF after you sign, the digital signature breaks and shows the document has been altered. Digital signatures are used for legal contracts that need proof of integrity.

For everyday tasks like a permission slip, a rental agreement, or a simple contract, an electronic mark is enough. The free tools described here provide electronic marks only. If you need a certificate-based digital signature, you would need software that supports certificate signing, such as a paid version of Adobe Acrobat.

Preparing the Signed PDF for Sending

After you place your mark, you may need to adjust the file before emailing or sharing it. Two common tasks are combining the signed page with other pages and reducing the file size.

Merge the signed page with the rest of the document

If you only signed one page of a multi-page document, use the Merge PDF tool on editpdf123.com to join that signed page with the remaining pages. Upload the signed page and the original document, then merge them into one PDF.

Compress the file for email

Large PDFs can be hard to email. Use the Compress PDF tool on editpdf123.com to shrink the file size while keeping the mark visible. This helps when your PDF is over the attachment limit.

  • Merge PDF: combine signed and unsigned pages.
  • Compress PDF: reduce file size for faster sending.

Both tools are free, online, and leave no watermark.