How to Sign a PDF on iPhone and Android (No App Needed)

PDFly guide · Updated October 2026

A contract lands in your inbox while you are away from your desk. Printing it is not an option, and installing yet another app just to sign one page feels like too much. The good news: any modern phone browser can do it, and your finger is a perfectly good pen.

What you need

• The PDF saved on your phone (from email, WhatsApp, Files, Google Drive or your downloads folder).
• A browser: Safari, Chrome, Samsung Internet, Firefox. Anything recent works.
• About two minutes.

Step by step

1. Open the tool. Go to PDFly Sign PDF and tap Choose a PDF. Pick your document from the file picker.
2. Choose "Sign it myself". Your pages appear below, one after another. Scroll to the page that needs your signature.
3. Tap Signature, then tap the page. A signature field appears where you tapped. Tap the field to open the signature box.
4. Draw, type or upload. Draw with your finger on the white pad (turn the phone sideways for more room), type your name in a handwriting style, or upload a photo of your signature.
5. Apply and adjust. Tap Apply, then drag the signature to the signature line and use the corner handle to resize it.
6. Download. Press the button to apply the signature and download the signed PDF. It lands in your Downloads or Files app, ready to send.

Tips for a clean signature on a small screen

• Rotate the phone to landscape while drawing. A wider pad gives smoother, more natural strokes.
• Zoom the page before placing the field so you can line it up with the signature line precisely.
• Use "Save as PNG" in the signature box to keep a transparent copy of your signature on your phone. Next time you can upload it instead of redrawing it.
• Add the date and initials with the Date and Initials buttons if the document asks for them.

Is it private?

When you sign it yourself, the PDF is processed inside your phone's browser. It is not uploaded to a server, so a lease, an ID copy or an employment contract stays on your device. (Only the "Request a signature" option, where someone else must sign, stores the file temporarily on the server so the other person can open it.)

Common problems

• The signature looks shaky. Press Clear and try again, slower, in landscape.
• The file will not open. Make sure it is a real PDF under 20 MB. A large scan can be shrunk first with Compress PDF.
• The download seems to vanish. On iPhone, look in the Files app under Downloads. On Android, check the Downloads folder or the browser's download list.