How to Add Digital Signatures to PDFs in an Editor App (2026)
To add a digital signature to a PDF, use RaptorPDF's free signing tool: upload your PDF, draw or type your signature, place it, and download. For cryptographic digital signatures (used in legal and enterprise contexts), Adobe Acrobat or DocuSign provide certificate-based signing. This guide explains both types and when to use each.
In This Guide
Electronic vs Digital Signatures: What's the Difference?
These terms are often confused but mean different things:
- Electronic signature — Any electronic mark indicating intent to sign (drawn, typed, or image). Legally binding under ESIGN Act and UETA in the US. Created with tools like RaptorPDF, Adobe Acrobat, or iOS Markup.
- Digital signature — A cryptographically secured signature using a digital certificate that verifies identity and ensures the document hasn't been altered. Used in high-security contexts like pharmaceutical, financial, and government documents.
For most everyday use — contracts, agreements, HR forms, rental applications — electronic signatures are legally valid and sufficient.
Add Your Signature to a PDF for Free (3 Steps)
1 Open the Signing Tool
Go to RaptorPDF's Sign PDF tool. Upload your PDF — no account required.
2 Create Your Signature
Draw with your mouse or touchscreen, type your name (select a style), or upload an image of your handwritten signature.
3 Place and Download
Click where you want your signature to appear. Resize if needed. Click Download — your signed PDF is ready instantly.
Sign PDFs Free — No Account Needed
Draw, type, or upload your signature. Works on any device.
Sign PDF NowHow to Add Signatures on Different Platforms
On Mac
Use Preview (built-in): Markup toolbar > Signature tool > Trackpad or camera signature. Or use RaptorPDF in Safari for cross-platform consistency.
On iPhone/iPad
Files app > open PDF > Markup > + button > Signature. Or use RaptorPDF in Safari for additional features.
On Windows
No built-in option. Use RaptorPDF in any browser, or Adobe Acrobat Reader (free, basic signing).
On Android
Adobe Fill & Sign (free) or RaptorPDF in Chrome work well on Android. Samsung devices also have a built-in PDF annotation capability.
Are Electronic Signatures Legally Binding?
In the United States, electronic signatures are legally binding under the ESIGN Act (2000) and UETA. They have the same legal status as handwritten signatures for most commercial and personal documents. Similar laws exist in the EU (eIDAS), UK (Electronic Communications Act), and most countries worldwide.
Exceptions where handwritten or notarized signatures may still be required: wills, court orders, certain real estate transactions, and regulated pharmaceutical documents.
Frequently Asked Questions
How do I add a digital signature to a PDF for free?
Use RaptorPDF's free signing tool: upload your PDF, draw or type your signature, place it on the document, and download. No account or payment required. For cryptographic digital signatures, Adobe Acrobat Pro is needed.
Are electronic signatures on PDFs legally valid?
Yes. Electronic signatures are legally binding in the US (ESIGN Act, UETA), EU (eIDAS), and most countries worldwide. They're valid for contracts, agreements, HR documents, and most commercial transactions.
What's the difference between a digital and electronic signature?
An electronic signature is any electronic indicator of intent to sign (drawn, typed, or image). A digital signature is a cryptographic certificate that verifies identity and ensures document integrity. Both are legal; digital signatures offer stronger security and tamper detection.
Can I add a signature to a PDF on iPhone?
Yes. Use the Files app Markup tool (built-in, free) or RaptorPDF in Safari. Both create legally valid electronic signatures with no watermarks.
Does RaptorPDF support digital certificate signatures?
RaptorPDF creates electronic signatures (drawn or typed), which are legally valid for most purposes. For certificate-based digital signatures required in enterprise or regulated industries, use Adobe Acrobat Pro or a dedicated e-signature platform like DocuSign.
Related Resources
- Sign PDF Tool — Free electronic signature tool
- Complete PDF Signing Guide
- PDF Security Guide
- Protect PDF — Add passwords and signatures