How to Sign Documents on Your Phone (iPhone and Android)

The method that works on any phone

A browser-based signer works the same on an iPhone, a Pixel, a Galaxy or a tablet, so you only need to learn it once.

1. Open multidocs.app/sign-pdf in Safari or Chrome.
2. Tap “Choose document.” Pick a PDF, a photo of the paper, or tap “Scan a paper document” to use the camera.
3. Choose “Just me” and tap “Add my signature.” Sign with your finger.
4. Tap where it goes. Add the date, your name, initials or a checkbox if the form asks.
5. Tap “Finish” and download it or email it.

It's free and unlimited when you sign alone, with no watermark. The file is processed on your phone and isn't uploaded. The signed PDF ends with a signature record (date, time and a SHA-256 fingerprint of the document) that anyone can check at /verify.

On iPhone: Markup

iPhones have a signing tool built in. Open the PDF in the Files app or tap the attachment in Mail, tap the Markup button (the pen tip), then “+” › “Add Signature.” Draw your signature once and the iPhone saves it. Drag it into place, tap “Done,” and share it. Full steps, including Mail replies and scanning paper: how to sign a PDF on iPhone.

On Android

Android phones don't share one built-in tool. The reliable options are the browser method above, or the free Adobe Acrobat Reader app (open the PDF › edit › Fill & Sign › create a signature › tap to place it). Recent versions of Google Drive also let you write on a PDF with a pen. Step by step: how to sign a PDF on Android.

Sign by type of document

When you need someone else's signature

This is where most people get stuck: you can sign on your phone, but how do you get a client, a tenant or a parent to do the same? Sending the PDF and asking them to “sign and send it back” usually means a blurry photo of a printout a week later.

Instead, send it for signature. From the same page:

1. Upload the document and choose “Other people” (or “Others and me”).
2. Tap “Mark where they sign”, place the box and add any field you need: name, date, initials, address, a checkbox, or even a request to attach a photo of an ID or a document.
3. Enter their email or mobile number. Text and WhatsApp open on your phone with the message ready, sent from your own number. Or copy the link.

They open it on their phone, sign with a finger and you receive one email with the signed PDF and its certificate of completion. If they forget, we send email reminders every two days, up to three times. Up to 20 people can sign the same document, at the same time or in order. The free plan includes 15 requests a month; see send a document for signature or, for texts, send for signature by text.

Tips for signing on a small screen

• Turn the phone sideways when you draw your signature; you get more room.
• Sign big and slow. It shrinks to fit the box.
• Zoom in on the page before you place the signature so it lands on the line.
• Check every page: long contracts often need initials on each one.
• Save the signed copy somewhere you'll find it again, like a “Signed” folder in Files or Drive.

Is a phone signature legally valid?

Yes, for nearly all private documents in the US. The ESIGN Act says a signature or contract can't be denied legal effect “solely because it is in electronic form” (15 U.S.C. § 7001(a)), and it defines an electronic signature broadly enough to include a finger-drawn one (§ 7006(5)). Nearly every state says the same in its version of the UETA. Exceptions include wills and certain court and family law papers: see documents that can't be e-signed. In a dispute, what matters is proving who signed, which is what an audit trail is for.