How to sign a document on your phone, and what each method proves

To sign a document on your phone, open it in a tool the phone already has: Markup on an iPhone, Google Drive, Files by Google or Samsung Notes on Android. Draw your signature, drag it into place, save a copy and send it back. If it arrived as a link from a signing service, sign inside the link instead.

The two routes leave different evidence. A built-in tool puts a picture of your signature on the page; a signing link also records who signed and when. Chaindoc in your phone's browser works the second way.

What's in your inbox decides which tool you need.

• A PDF attachment. The usual case, covered device by device below.
• A "Review and sign" link. That's a signing service such as DocuSign, Adobe Acrobat Sign or Chaindoc. Sign inside the link; that's where the sender expects your signature, not in a file you mail back.
• A Word file. Workable but clumsy, see the Word section.
• A photo of a paper page. Open it like a PDF; if it's blurry, ask for the original.

If someone only wants an image of your signature, you can make a signature image in your browser, but think twice: a loose copy of your signature can land on any document.

Apple's tool is Markup, and it's built into Files, Mail, Notes and Photos.

1. 1.
   Open the document. If iPhone asks, open it in the Files app and tap Save.
2. 2.
   Tap the Markup button.
3. 3.
   Tap the add button (+), then Add Signature.
4. 4.
   Sign with your finger and tap Done.
5. 5.
   Drag the signature into place. Drag a blue dot on its frame to resize it.
6. 6.
   Tap Done, then share or save the file.

Steps per Apple's iPhone User Guide, iOS 27.

A PDF that came by email

In Mail, tap the attachment, tap the Markup button and sign. Tap Done, and Mail offers to reply to the sender with the marked-up file or save it to Files.

Saved signatures

iPhone keeps every signature you create, labelled as your full name, a nickname or initials, and you delete old ones under Add or Remove Signature. Draw it once, properly, at a table. Here's how to settle on a signature worth saving.

For your own paperwork, Markup is honestly all you need. Just know what it hands over: a PDF with a drawing on it, and nothing in the file that says you drew it. On a computer the tools differ; see signing on a Mac or Windows PC.

Android has no single signing button, so you sign with a pen tool. There are three free routes.

Google Drive

1. 1.
   Open the PDF in the Google Drive app.
2. 2.
   Tap the annotate button at the bottom right.
3. 3.
   Pick the pen and sign with your finger or a stylus.
4. 4.
   Save, either over the original or as a copy under a new name. The copy leaves the original unmarked.

It needs Android 6.0 Marshmallow or later, according to Google Drive Help.

Files by Google

Open the PDF, tap Edit and sign with the pen. Tap Save copy, then Upload: the copy goes to your Google Drive and the file on the phone stays clean.

Samsung Notes on a Galaxy

Touch and hold Create note, tap Import PDF, pick the file and tap Done. Sign on the page and tap Back to save. To export it, open the note and tap More options, Save as file, PDF file. Importing makes a copy, so the original stays untouched. These steps come from Samsung's support page, which warns that some tools vary by model.

All three draw ink strokes on the page. None of them records who held the pen.

Word for iPhone and Android takes a signature directly: open the file, tap the Draw tab, pick a pen and sign with your finger. On iPhone, Microsoft's support page says to turn off Draw with Touch afterwards, so a stray thumb doesn't add marks.

We'd still ask for a PDF. A Word file stays editable after you sign it, so the text around your signature can change without a trace. If a .docx is all you get, sign it and send it back as a PDF.

Here the sender has uploaded the file to a signing service and marked where you sign. On a phone:

• Tap the link; the document opens in your browser.
• Accept the consent screen, if there is one.
• Tap each marked field, draw or adopt a signature, then Finish.

You rarely need an app or an account. Adobe says signers of its Acrobat Sign requests need no downloads, and DocuSign says you can sign its requests without an account. Chaindoc works the same way: recipients sign through a link in the phone's browser. Its own iOS and Android apps are still in development, not in the stores, so the browser is the app for now.

What a link adds is the record: an audit trail of who signed and when. In Chaindoc the document's version hash goes on a blockchain when it's published for signing, and each signer's proof is recorded when signing completes, so a later edit to the file shows up as a mismatch.

One caution. Phishing emails copy these links, and a phone screen hides most of the clues. Not expecting a document? Check a signing link before you tap it.

Every method below is free for the person signing. They differ in what the other side ends up holding. So if you're asking how you can sign a document on your phone for free and still have it hold up later, read the last column first.

In the US, usually yes, and the phone has nothing to do with it. Section 101(a) of the ESIGN Act (Public Law 106-229) says a signature or contract in interstate or foreign commerce "may not be denied legal effect, validity, or enforceability solely because it is in electronic form." Section 106(5) defines an electronic signature as "an electronic sound, symbol, or process" attached to a record and adopted with the intent to sign it. A finger-drawn signature in Markup fits that definition. States add their own layer through the Uniform Electronic Transactions Act, which each state enacts separately.

One rule matters more on a phone than people expect. When a business must give you information in writing and wants to do it electronically, section 101(c) makes it ask for your consent first and tell you what hardware and software you'll need to open and keep the records. That's why many signing links open with a consent screen. Don't tap past it: it's where you agree to get the rest on a screen instead of on paper.

In the EU, Article 25(1) of the eIDAS Regulation says an electronic signature can't be denied legal effect or refused as evidence just because it's electronic. Only a qualified electronic signature is guaranteed the legal effect of a handwritten one across the EU, under Article 25(2), and that takes a certificate from a qualified trust service provider, not a drawing.

ESIGN also leaves some documents out: wills, codicils and testamentary trusts, adoption and divorce papers, court orders and a handful of consumer notices. See the documents that still need ink.

So the law rarely asks whether a phone signature counts. If there's a fight, it's over who drew it. Anyone with a copy of a signed PDF can paste the same picture onto another page, while an audit trail ties the signature to an email address, a time and one version of the document.

Each of these takes a second to avoid and a long time to fix.

• Signing a screenshot. It's a low-resolution picture of the page, the small print blurs, and the other side may refuse it. Sign the file itself.
• Saving over the original. Drive and Files by Google both offer a copy. Take it.
• Sending a loose image of your signature. Ask what it's for first.
• Tapping a signing link you weren't expecting. Fake "please sign" emails are a standard phishing format.
• Skimming because the screen is small. Page 7 binds you even if you only read page 1.
• Not keeping your copy and the completion email.

Sometimes you're the one who needs the signature, and all you have is a phone. Emailing a PDF for the other side to draw on works, but leaves you with a picture, no record and a lot of chasing.

In Chaindoc, which runs in your phone's browser, you upload the PDF, add up to 10 people and send the document for signature. Everyone gets a link at once; a fixed signing order comes with approval routes on the Business plan. Each person signs on their own device without installing anything, and you follow the status from the same tab. KYC identity checks are available on paid plans when a deal needs them, never required.

The Free plan covers 5 signatures a month with no card; Chaindoc's plans list the rest. So if you're still weighing how to sign a document on your phone so it stands up later, that's the answer: a link, a tap and a record you can point to.