Method 1: The iOS Markup tool
Free · No app · Built into iOS
iOS has a signing tool built into Files, Mail and any system PDF viewer. No account or download required.
- 1Open the PDF from Files, Mail, or any app that displays it.
- 2Tap the Markup icon (the pen tip in the bottom corner).
- 3Tap the + button and select Signature.
- 4If it's your first time, draw your signature with your finger. It saves to your Apple ID for reuse.
- 5Drag the signature into place, resize it, and tap Done.
- 6Share or save the signed PDF.
Method 2: Sign directly from Mail
Free · No app · Best when you received the PDF by email
If the PDF arrived by email, you don't even need to leave the Mail app. It's the fastest method when the document is already in your inbox.
- 1Open the email and tap the attachment to preview it.
- 2Tap the Markup icon (pen over a square).
- 3Add your signature as in the previous method.
- 4Tap Done → Reply with attachment to send the signed document back to the sender.
Fast, and you never leave your inbox. Like Markup, it leaves no verifiable digital trail.
Method 3: Adobe Acrobat Reader
Free app · Account required
Adobe Acrobat Reader has a free iPhone app that signs PDFs in a more structured way, with positionable signature fields.
- 1Download Adobe Acrobat Reader from the App Store.
- 2Open the PDF → tap Edit → Fill & Sign.
- 3Place the signature field where it belongs and draw or import your signature.
- 4Save and share.
Method 4: SignQuick
RecommendedLegally valid signature · Full audit trail · Signer installs nothing
If the document actually matters legally — a service agreement, an NDA, an accepted quote — the methods above fall short. Nobody can verify who signed, when, or from where. That's where SignQuick comes in.
SignQuick is an iPhone app built specifically to make signatures traceable and verifiable. Its key difference: the signer doesn't need to install anything. They just open a link in their browser.
How it works in 3 steps
You create the request
From the SignQuick app on your iPhone or the web dashboard. Upload the PDF and send a unique link to the signer by email, WhatsApp or any channel. Only they can use it.
The signer opens the link in their browser
No accounts, no downloads. They see the full document, draw their signature with a finger, and accept the electronic signature clause. Works on iPhone, Android or desktop.
The signature is recorded
With a precise timestamp, the signer's IP address, and a cryptographic SHA-256 hash guaranteeing the document's integrity. It all lands in the audit trail, and you get notified instantly.
Why this matters
iOS Markup adds a signature image to a PDF. That's it. SignQuick generates a trail of electronic evidence: who signed, when, from what device and IP address. If there's ever a dispute, you have verifiable proof. With a scribble in Markup, you have nothing.
Which method should you use?
| Situation | Recommended method |
|---|---|
| Personal form or low-risk authorization | Native iOS Markup |
| Quick reply to a PDF received by email | Markup from Mail |
| Occasional signing with a more visual interface | Adobe Acrobat Reader |
| Contract, agreement or legally significant document | SignQuick |
Frequently asked questions
Can I sign a PDF on iPhone without downloading an app?
Yes. The built-in Markup tool works from Files, Mail or any system PDF viewer with no install required. It adds a signature image but no audit trail.
Is signing a PDF with iOS Markup legally valid?
It can count as a simple electronic signature under ESIGN and eIDAS if there is evidence of intent to sign, but Markup itself keeps no record of who signed, when or from where — that weakens it for anything you might need to prove later.
What is the fastest way to sign a PDF someone emailed me?
Open the email in Mail, tap the attachment to preview it, then use Markup directly inside Mail and reply with the signed file attached — no need to leave the app.
How do I send a PDF to someone else for signature from my iPhone?
Use an eSignature app like SignQuick: upload the PDF, add the signer's email or phone number, and send a secure link. They sign in their browser with no account needed, and you get notified with a full audit record.
Do I need Adobe Acrobat to sign PDFs on iPhone?
No. iOS has a free built-in signing tool. Adobe Acrobat Reader adds more structured signature fields, but its free tier does not cover sending requests to other people — that requires a paid subscription.