How to sign a PDF on your phone without installing an app

Last updated: September 17, 2026

The contract, the school permission slip or the delivery note arrives on WhatsApp or by email, with "sign and send it back". You have no printer, and the app stores want you to install something and create an account first. You don't need either: your phone's browser is enough.

Step by step

Save the PDF on your phone. On iPhone, open it and use Share → Save to Files. On Android, tap Download; it goes to Downloads.
Open Sign PDF in Safari or Chrome and tap to choose the file.
Sign with your finger in the white box. Turning the phone sideways gives you more room. If it doesn't look right, tap Clear signature and try again.
Choose the page (the last one is selected for you), the position (bottom right, bottom left, top or bottom centre) and the size.
Tap Sign PDF. The signed copy is saved as -signed.pdf in Files → Downloads (iPhone) or Downloads (Android).
Send it back from there with Share, WhatsApp or your email app.

Before signing: fill it in

If the document has blanks for your name, date or ID number, fill them first with Fill PDF Form and sign the result. Doing it in that order keeps a single, clean file.

What this method doesn't do

It signs one page at a time. If every page needs initials, sign the output again and pick the next page.
The signature goes in a corner or at the bottom centre. If the form has a signature box in the middle of the page, those positions may not match it. On iPhone, the Files app has a built-in signature tool (Markup → + → Signature) that lets you drag it anywhere, with no app to install.

Is a drawn signature valid?

For many everyday documents, yes: permission slips, delivery notes, rental inventories, quotes, agreements between individuals. Legally it is a simple electronic signature. Some procedures, especially with government agencies, banks and certain contracts, require a qualified electronic signature or an official digital ID, and a drawn signature won't be accepted there. If you're not sure, ask whoever sent you the document which signature they accept.

Your signature stays on your phone

A signed document plus a copy of your signature is exactly what you don't want sitting on someone else's server. robinpdf does everything in your phone's browser: the PDF isn't uploaded, and your signature isn't saved anywhere, not even for next time.

Frequently asked questions

Does it work on iPhone and Android?

Yes, in any up-to-date browser: Safari, Chrome, Firefox, Samsung Internet.

Can I save my signature for next time?

No, on purpose: nothing is stored. Drawing it again takes a couple of seconds.

Can I use a stylus?

Yes. A stylus or Apple Pencil gives a finer line than a finger.

Sign a PDF on your phone →