How to Sign PDF Documents Free Online (2025 Complete Guide)

To sign a PDF document electronically, upload your file to an online signing tool, create your signature by drawing or typing, place it on the document, and download. The fastest free method is using RaptorPDF's Sign PDF tool - it processes files locally in your browser, requires no account, and creates legally valid electronic signatures that work for contracts, agreements, and official documents.

Quick Steps: Sign a PDF in 3 Steps

Need to sign a PDF right now? Here's the fastest free method:

5 Ways to Sign PDF Documents

There are several methods to add your signature to a PDF. Here's a comparison of the most popular approaches:

How to Sign a PDF on iPhone or iPad

There are several ways to sign PDFs on your Apple mobile device:

Method 1: Using Files App (Built-in)

1. Open the PDF in the Files app
2. Tap the Markup icon (pen tip in a circle)
3. Tap the + button at the bottom
4. Select Signature
5. Draw your signature with your finger or Apple Pencil
6. Tap Done, then position and resize the signature
7. Tap Done again to save

Method 2: Using Safari (Online Tool)

1. Open Safari and go to RaptorPDF Sign PDF
2. Upload your PDF from Files or iCloud
3. Draw your signature on the touchscreen
4. Place it on the document and download

How to Sign a PDF on Mac (Without Additional Software)

Mac users can sign PDFs using Preview, which comes pre-installed on every Mac:

Using Preview (Built-in)

1. Open your PDF in Preview (right-click > Open With > Preview)
2. Click the Show Markup Toolbar button (or press Shift+Command+A)
3. Click the Signature icon (looks like a signature)
4. Choose how to create your signature:
   • Trackpad: Draw with your finger on the trackpad
   • Camera: Hold a paper signature up to your camera
   • iPhone: Draw on your iPhone's screen
5. Click Done after creating your signature
6. Click on the document where you want the signature
7. Resize by dragging the corners, then save (Command+S)

How to Sign a PDF on Windows

Windows doesn't have built-in PDF signing like Mac, but there are several free options:

Method 1: Online Tool (Recommended)

1. Open your browser and go to RaptorPDF Sign PDF
2. Upload your PDF file
3. Create your signature by drawing with your mouse
4. Position it on the document and download

Method 2: Adobe Acrobat Reader (Free)

1. Download and install Adobe Acrobat Reader (free)
2. Open your PDF in Acrobat Reader
3. Click Fill & Sign in the right panel
4. Click Sign and choose Add Signature
5. Type, draw, or upload your signature image
6. Click on the document to place your signature
7. Save the signed PDF

Method 3: Microsoft Edge (Built-in Browser)

1. Open the PDF in Microsoft Edge
2. Click the Draw tool in the toolbar
3. Draw your signature directly on the document
4. Click Save or Save As

How to Sign a PDF on Android

Android devices have several options for signing PDFs:

Method 1: Google Drive / Files

1. Open the PDF in Google Drive or Files by Google
2. Tap the Edit or Annotate option
3. Use the pen tool to draw your signature
4. Save the document

Method 2: Adobe Fill & Sign (Free App)

1. Download Adobe Fill & Sign from Play Store
2. Open your PDF in the app
3. Tap where you want to sign
4. Create your signature by drawing with your finger
5. Save and share the signed document

Method 3: Browser-Based Tool

1. Open Chrome and go to RaptorPDF Sign PDF
2. Upload your PDF
3. Draw your signature on the touchscreen
4. Download the signed document

Are Electronic Signatures Legally Binding?

Yes, electronic signatures are legally binding in most countries. Here's the legal framework:

United States

• ESIGN Act (2000): Federal law giving electronic signatures the same legal validity as handwritten signatures
• UETA (1999): Uniform Electronic Transactions Act adopted by 47 states
• What's covered: Contracts, agreements, authorizations, most business documents

European Union

• eIDAS Regulation (2014): Provides legal framework for electronic signatures across all EU member states
• Three levels: Simple, Advanced, and Qualified electronic signatures

Documents That May Require Handwritten Signatures

Electronic vs Digital Signatures: What's the Difference?

These terms are often confused, but they're technically different:

Feature	Electronic Signature	Digital Signature
Definition	Any electronic mark indicating agreement	Cryptographically secured signature
Examples	Drawn signature, typed name, checkbox	Certificate-based PKI signature
Security	Basic	High (tamper-evident)
Identity Verification	Intent-based	Certificate-based
Legally Binding	Yes	Yes
Best For	Everyday contracts, agreements	High-security documents, compliance

For most personal and business use, electronic signatures are sufficient and legally valid. Digital signatures with certificates are typically used in high-security environments, government documents, or when strong identity verification is required.

How to Create a Reusable Signature

Creating a reusable signature saves time when you sign documents frequently:

Best Practices for Reusable Signatures

1. Create a clean signature image:
   • Sign on white paper with a dark pen
   • Take a photo in good lighting
   • Crop tightly around the signature
   • Use an app to remove the background (make it transparent)
2. Save in multiple formats:
   • PNG with transparent background (best for documents)
   • Save to cloud storage for access anywhere
3. Use platform features:
   • iOS/macOS: Saved signatures sync via iCloud
   • Adobe: Signatures saved to your Adobe account
   • Online tools: Some allow saving signatures locally

How to Verify a Signed PDF

If you receive a signed PDF and need to verify its authenticity:

For Digital Signatures (Certificate-Based)

1. Open the PDF in Adobe Acrobat Reader
2. Click on the signature panel or the signature itself
3. Look for "Signature is valid" or similar message
4. Click "Signature Properties" for details about:
   • Who signed the document
   • When it was signed
   • Whether the document was modified after signing

For Electronic Signatures (Non-Certificate)

Standard electronic signatures don't have built-in verification. To ensure authenticity:

• Confirm the signature matches the expected signer
• Check if the document came from a trusted source
• Look for audit trail or timestamp if available
• Contact the signer directly if in doubt

Security & Privacy Tips for Signing PDFs

Keep your documents and signatures secure:

Choosing a Safe Signing Tool

• Local processing: Choose tools that process files in your browser, not on servers
• No account required: Tools that work without accounts can't store your documents
• HTTPS: Ensure the website uses secure encryption
• Privacy policy: Read what happens to your uploaded files

Best Practices

• Password protect sensitive signed documents
• Keep copies of all signed documents
• Use secure sharing methods (encrypted email, secure file sharing)
• Don't sign blank pages - only sign complete documents
• Review before signing - read the entire document carefully

PDF Signing Tool Comparison

Feature	RaptorPDF	Adobe Reader	DocuSign	Preview (Mac)
Price	Free	Free / $23+	$10+/month	Free
No Installation	✓	✗	✓	✓
Local Processing	✓	✓	✗	✓
Works on All Devices	✓	Desktop only	✓	Mac only
Draw Signature	✓	✓	✓	✓
Type Signature	✓	✓	✓	✗
Request Signatures	✗	Paid only	✓	✗
Best For	Quick signing	Adobe users	Business	Mac users

Frequently Asked Questions

Related Resources

• Sign PDF Tool - Free online PDF signing
• Add Password to PDF - Protect signed documents
• PDF Security Guide - Password protection and encryption
• All PDF Guides - Comprehensive PDF tutorials