How to Add a Signature to a PDF for Free

Quick summary: To add a signature to a PDF for free on Mac, open it in Preview, open the Markup toolbar, click the Signature tool (the cursive “S” icon), draw or scan your signature, then drag it onto the page. On Windows, open the PDF in Adobe Acrobat Reader (free) → Fill & Sign → Sign → Add Signature. On iPhone, open the PDF in the Files app Markup tool → tap ”+” → Signature.

Adding a signature to a PDF takes under two minutes on any platform. Every major operating system includes a signing tool for free — no Adobe subscription required. Once signed, upload the document to our AI-powered PDF tool to summarize or review the contents before sending.

Electronic signature vs. digital signature

Before choosing a method, it helps to understand the difference:

Type	What it is	Legal standing
Electronic signature	A drawn, typed, or image-based mark	Legally binding in most countries for most contracts (eSign Act, eIDAS)
Digital signature	A cryptographic certificate tied to your identity	Higher assurance; required for regulated industries, government documents

The methods below all produce electronic signatures. For legally certified digital signatures, you need a certificate from a trusted authority (DocuSign, Adobe Sign, or a government-issued certificate).

How to add a signature to a PDF on Mac — Preview

Preview on macOS makes signing a PDF straightforward:

Draw your signature

1. Open the PDF in Preview.
2. Click View → Show Markup Toolbar (or the toolbox icon).
3. Click the Signature tool (the cursive “S” with a line).
4. Click “Create Signature”.
5. Choose Trackpad or Camera:
   • Trackpad: Draw your signature with your finger. Press any key when done.
   • Camera: Sign your name on white paper, hold it up to the camera, and Preview captures it.
6. Click Done to save.
7. Click the signature in the Markup toolbar to insert it on the page.
8. Drag and resize the signature to position it.
9. Save with Cmd + S.

Preview saves signatures in your macOS Keychain — you only draw it once and it is available in any future PDF.

Type your name as a signature

For a typed signature in Preview, use the Text tool (T icon) to add your name in a cursive-looking font. This is less formal but sufficient for many informal agreements.

How to add a signature to a PDF on Windows

Method 1: Adobe Acrobat Reader (free)

Adobe Acrobat Reader’s free tier includes signing:

1. Open the PDF in Adobe Acrobat Reader.
2. Click Tools → Fill & Sign (or the pen icon in the toolbar).
3. Click “Sign yourself” → “Add Signature”.
4. Choose from three options:
   • Type — enter your name; Acrobat renders it in a signature-style font.
   • Draw — use your mouse or touchscreen to draw.
   • Image — upload a photo of your handwritten signature (PNG with transparent background works best).
5. Click Apply.
6. Click on the page where you want to place the signature.
7. Drag to reposition. Click outside to deselect.
8. Save with Ctrl + S or File → Save.

Method 2: Microsoft Edge (for typed signatures)

Edge’s built-in PDF tools include a Draw tool that can place a hand-drawn signature:

1. Open the PDF in Edge.
2. Click Draw in the toolbar and choose a black, thin pen tip.
3. Draw your signature on the page.
4. Press Ctrl + S to save.

This works best on touchscreen devices.

How to add a signature to a PDF on iPhone

1. Open the PDF in the Files app.
2. Tap the file to open it in Quick Look.
3. Tap the Markup icon (pencil in a circle) in the top-right corner.
4. Tap the ”+” button at the bottom right.
5. Select “Signature”.
6. Draw your signature with your finger on the signature pad.
7. Tap Done.
8. Drag and resize the signature on the page.
9. Tap Done → “Save File” (or share to another app).

iOS saves your signature for reuse in future markups. You can manage saved signatures by tapping the ”+” → Signature again.

How to add a signature to a PDF online — free

Search for “sign PDF free” and choose any well-reviewed browser-based tool:

1. Upload your PDF.
2. Use the signature tool to draw, type, or upload your signature.
3. Place it on the page.
4. Download the signed PDF.

Privacy note: Your file is sent to a remote server. For confidential contracts or legal documents, use an offline method.

How to use a signature image (photo of your handwritten signature)

If you have a clear photo of your handwritten signature, you can use it in any platform:

1. Photograph your signature on white paper in good lighting.
2. In a photo editing app, remove the white background — on iPhone use the Photos background removal tool; on Mac, drag the image into Preview, select the white background with the Instant Alpha tool, and delete it.
3. Save as PNG (PNG supports transparent backgrounds; JPEG does not).
4. In Acrobat Reader: Fill & Sign → Add Signature → Image → upload the PNG.
5. In Preview: drag the PNG directly onto the PDF page.

What to do after signing

After adding your signature:

• Flatten the PDF before sending — this locks the signature into the page so it cannot be moved. See how to flatten a PDF for free.
• Password protect it if the document is sensitive. See how to password protect a PDF for free.
• Compress it if the signature image made the file larger. See how to compress a PDF for free.

Frequently Asked Questions (FAQ)

Is an electronic signature on a PDF legally valid?

In the United States, the ESIGN Act (2000) makes electronic signatures legally binding for most contracts. The EU’s eIDAS regulation does the same for Europe. The main exceptions are wills, real estate deeds in some jurisdictions, court documents, and certain government forms — check the specific requirements before signing.

Can I remove a signature I added?

If the PDF has not been flattened, yes: open it in Preview or Acrobat Reader, select the signature object, and delete it. If the PDF was flattened after signing, the signature is permanently merged into the page and cannot be removed without visible damage to the document.

How do I verify someone else’s signature on a PDF?

Electronic signatures from draw/type/image methods have no cryptographic verification — you cannot confirm they are genuine without additional context. Cryptographic digital signatures (from DocuSign, Adobe Sign, or a government certificate) can be verified via the Signatures panel in Acrobat Reader → check the certificate chain and timestamp.

Why does my signature look blurry after saving?

The signature was placed at a small size and then the PDF was saved at low resolution. Use a high-resolution signature image (at least 300 DPI), or draw it larger before placing it. In Preview, zoom in on the page before dragging the signature to place it at a larger initial size.

Can I sign a password-protected PDF?

Not until you unlock it first. See how to remove a password from a PDF, sign it, then add a new password if needed.

How do I add a digital signature to a PDF that is already signed?

Additional signatories can add their signatures alongside existing ones without disturbing them. Use Preview on Mac (Markup toolbar → Signature) or Acrobat Reader (Fill & Sign → Sign yourself) to add a new signature in an available area of the page. If the PDF was flattened after the first signature, you can still place a new signature annotation on top — it just won’t have cryptographic verification linking it to the document.

How do I create a handwritten signature for a PDF?

In Preview on Mac: open the Markup toolbar, click the Signature icon, then choose “Create Signature” — draw on the trackpad with your finger or hold a signed paper to the webcam. In Acrobat Reader: go to Tools → Fill & Sign → Sign yourself → Add Signature → Draw. The drawn signature is saved and can be reused across documents without redrawing.