How to Sign a PDF on iPhone and Android for Free

Sign PDFs on Your Phone in Seconds

Need to sign a document but you are away from your computer? You are not alone. Over 60% of document signings now happen on mobile devices. Here is exactly how to sign a PDF on your iPhone or Android — completely free, no app required.

Method 1: Use a Browser-Based PDF Signer (Fastest)

The fastest way to sign a PDF on your phone is with a browser-based tool like SignQuick. Here is the step-by-step:

• Open SignQuick in your mobile browser (Safari, Chrome, etc.)
• Tap "Upload PDF" or drag your file into the upload zone
• Draw your signature using your finger on the touchscreen
• Tap anywhere on the document to place your signature
• Download your signed PDF — done!

The entire process takes under 30 seconds. Your file never leaves your device (it is processed entirely in your browser), so it is 100% private.

Method 2: iPhone Built-in Markup

iOS has a built-in Markup tool, but it has limitations:

• Open the PDF in Files app
• Tap the Markup icon (pen tip)
• Draw your signature
• Save

Limitations: No proper signature management, no audit trail, signatures look hand-drawn rather than professional, and the signed PDF cannot include metadata proving when it was signed.

Method 3: Android PDF Viewers

Some Android PDF viewers offer basic annotation, but:

• Most require a paid subscription for signature features
• No legal audit trail
• Limited formatting options

Why Browser-Based Signing Wins on Mobile

Tips for Better Mobile Signatures

• Use your finger, not a stylus — modern touch screens capture finger input more accurately
• Sign in landscape mode for more space
• Zoom in on the signature area before placing
• Save your signature for reuse on future documents

Is a Mobile Signature Legally Binding?

Yes! Under the ESIGN Act (US) and eIDAS (EU), electronic signatures are legally binding regardless of the device used. What matters is:

• Intent to sign — the signer deliberately placed their signature
• Consent — all parties agreed to use electronic signatures
• Record keeping — a copy of the signed document is retained

SignQuick generates a complete audit trail for every signature, making your mobile-signed documents legally valid.

Ready to Sign?

Open SignQuick on your phone right now — it works perfectly on any screen size. No account needed, no app to download, completely free for up to 5 documents per month.