How to Sign a PDF on iPhone and Android for Free (2026 Guide)

A contract lands in your inbox while you're away from your desk. The old workflow — print, sign with a pen, scan, email back — is a relic. Your phone can do the whole job in under a minute, for free, and the result is a cleaner document than a phone photo of a signed printout ever was.

There are three genuinely free ways to do it. The fastest is an online signer that works in any mobile browser; your phone also has built-in signing features most people never find. Here's how each one works.

Method 1: Sign online in your mobile browser (fastest, works on iPhone and Android)

This is the most reliable option because it works identically on every phone and needs no app install.

1. Open https://www.purepdf.net/sign-pdf in Safari (iPhone) or Chrome (Android).
2. Tap the upload area and choose your PDF from Files, Google Drive, or your downloads.
3. Choose how to create your signature:
   • Draw it with your finger or a stylus,
   • Type your name and pick a handwriting-style font,
   • Upload an image of your handwritten signature.
4. Drag the signature onto the line where it belongs. Resize it with the handles.
5. Download the signed PDF. The signature is embedded in the file itself, so it shows up correctly for anyone who opens it — on any device, in any PDF reader.

No signup, no watermark. The whole thing takes about 60 seconds once you've done it once.

Tip: Save your drawn signature in the tool so you can reuse it on the next document without redrawing it.

Method 2: iPhone's built-in Markup signature (no internet needed)

Every iPhone since iOS 10 has a hidden signing tool. It works offline and your signature is stored on the device for reuse.

From the Files app or Mail:

1. Open the PDF (tap the attachment in Mail, or open it in Files).
2. Tap the Markup icon (the pen tip inside a circle).
3. Tap the + button at the bottom, then choose Signature.
4. The first time, you'll be asked to draw your signature with your finger. It gets saved automatically for future documents.
5. Drag the signature into place, resize it, and tap Done.

Other places Markup lives on iPhone:

• Photos: open a screenshot or photo of a document, tap Edit → Markup.
• Notes: scan a paper document with the camera, then open it and tap the Share button → Markup.

The catch: Markup signatures are tied to your Apple device. If someone else picks up your unlocked phone, they could reuse your saved signature — so keep your phone locked with Face ID or a passcode.

Method 3: Android's built-in options

Android doesn't have one single signing tool across all phones, but you have good free options:

• Google Drive: open the PDF in Drive, tap the pencil/annotate icon, and use the markup tools to draw your signature.
• Files by Google / your manufacturer's PDF viewer: many include an annotate or "fill and sign" mode — look for a pen or signature icon in the toolbar.
• Adobe Acrobat Reader (free): the free tier lets you draw a signature and place it on the document.

If your phone's built-in viewer can't do it, fall back to Method 1 — the online signer works the same on Android as on iPhone.

Which method should you use?

Situation	Best choice
Quick one-off signature	iPhone Markup or PurePDF online signer
Same signature on many documents	PurePDF online signer (saved signature, works everywhere)
No internet connection	iPhone Markup / your phone's built-in viewer
Formal contract needing signer identity + timestamp	A dedicated e-signature service (DocuSign, Adobe Sign) — drawn signatures don't prove identity

For everyday paperwork — rental applications, school permission slips, HR forms, delivery confirmations — a drawn or typed signature placed on the PDF is accepted almost everywhere. For high-stakes contracts, use a service that records who signed and when.

5 tips for a signature that looks professional

1. Sign big, then shrink. Draw your signature large on the screen and scale it down — it renders smoother than signing tiny.
2. Use a stylus if you have one. Finger-drawn signatures look fine, but a cheap capacitive stylus gives cleaner strokes.
3. Keep the aspect ratio. Stretching a signature sideways is the fastest way to make it look fake.
4. Place it on the line, not above it. Zoom in before placing so the signature sits exactly on the signature line.
5. Check the export. Open the downloaded PDF and zoom in on the signature before sending — make sure nothing shifted during placement.

FAQ

Is a signature drawn on my phone legally valid? For most everyday documents, yes — electronic signatures are legally recognized in the US (ESIGN Act), the EU (eIDAS), the UK, India (IT Act), and most other countries. Regulated or high-value contracts may require certified e-signature platforms with audit trails.

Do I need to install an app to sign a PDF on my phone? No. PurePDF's online signer runs in your mobile browser, and both iPhone (Markup) and most Android phones have built-in annotation tools. Apps only add value if you need multi-signer workflows or audit trails.

Can I sign a PDF on iPhone without printing it? Yes — that's exactly what the Markup signature tool is for. Open the PDF in Files or Mail, tap Markup → + → Signature, and you're done.

Will the recipient see my signature correctly? Yes, as long as the signature is embedded in the PDF (all three methods above do this). Avoid sending a photo of a printed page — it can blur, crop, or skew the document.

Is it safe to sign documents with a free online tool? For non-sensitive documents, yes — but prefer tools that process the file in your browser rather than uploading it to a server, and avoid uploading highly confidential contracts to any free service you haven't vetted.