Guide
How to sign a PDF on an iPhone
Short answer
Open the PDF in the Files app or as a Mail attachment, tap the Markup button, tap the Add button (+), choose Add Signature, sign with your finger and tap Done, then drag the signature into place. That puts your own signature on the file for free; to collect another person's signature with a record of who signed, send the PDF from Sign PDF, which works in Safari on the same phone.
Updated 25 October 2026
Step by step
- 1
Save the PDF to Files
Open the PDF, tap the Share button and choose Save to Files, or open it straight from a Mail attachment.
- 2
Open Markup
Tap the Markup button, the pen tip icon, to show the Markup toolbar.
- 3
Choose Add Signature
Tap the Add button (+) in the toolbar, then tap Add Signature. Saved signatures appear here if you have made one before.
- 4
Sign with your finger
Sign in the box. Tap Clear to start again, then tap Done when you are happy.
- 5
Move and resize it
Drag the signature onto the line and use the blue dots on its border to make it fit.
- 6
Add the date if asked
Tap the Add button, choose Text, type the date and drag it next to your signature.
- 7
Tap Done and send it back
Tap Done to save, then share the file or reply in Mail with the signed copy.
Signing a PDF in the Files app
Markup is built into iOS, so there is nothing to install. Save the PDF to Files first: if it arrived in Messages or WhatsApp, open it, tap the Share button and choose Save to Files. Then open it from the Files app.
Tap the Markup button (the pen tip in a circle) at the top or bottom of the screen. In the Markup toolbar, tap the Add button, the plus sign, and choose Add Signature. Sign in the box with your finger. If it comes out wobbly, tap Clear and try again, and turning the phone sideways gives you more room. Tap Done.
The signature drops onto the page. Drag it to the signature line and pull the blue dots on its border to resize it. Tap Done to save. Files saves over the original, so duplicate it first (long-press, then Duplicate) if you want to keep an unsigned copy.
Signing a PDF attachment in Mail
If the PDF came by email, you can sign and reply in one go. Reply to the message, tap in the body, tap the attachment button in the format bar and attach the PDF, or forward the original with the attachment. Tap the attachment, then the Markup button, then the Add button and Add Signature.
When you tap Done, Mail asks whether to reply with the marked-up copy. The signed version goes back as the attachment. Apple's Markup support page describes the same route for photos.
Saved signatures, initials and dates
Your iPhone keeps signatures you create, so next time Add Signature shows them as a list. You can save more than one, which is handy for keeping your initials as a separate small signature. You can remove ones you no longer need from the same list.
For the date, tap the Add button and choose Text, type the date, then drag the box beside your signature. On recent iOS versions, Markup can also recognise form fields and offer to fill name and address boxes for you.
When Markup is not enough
Markup stamps a picture of your signature on the page. That is fine when someone has sent you a document to sign and is happy to receive it back by email. It is not a way to collect a signature from someone else: if you send a PDF to a client and ask them to Markup it, you get back an image with no record of who drew it, from where, or whether the text changed in between.
To get another person's signature from your phone, open signpdf.ai in Safari, upload the PDF from Files or a photo of a single printed page (export iPhone HEIC photos as JPEG first, as we do not read HEIC yet), check the boxes we place, add the signer's email and send. They confirm a six-digit code and sign in their own browser. You both receive a sealed PDF with a certificate showing their verified email, IP address, device and the time they signed.
We do not have a native iPhone app; Sign PDF runs in the browser. Plans start at $5 a month.
Questions people ask
Where is the Markup button on iPhone?
It is the small pen tip in a circle, shown when you open a PDF in Files, Mail or Photos. In some apps it sits under the Share button or the More (three dots) button.
Does signing in Files change the original PDF?
Yes, Files saves the markup into the file you opened. Long-press the file and choose Duplicate first if you want to keep an unsigned copy.
Can I sign a PDF on iPhone without an app?
Yes. Markup is part of iOS and needs no download. To collect someone else's signature, Sign PDF runs in Safari, so there is still nothing to install.
Can my client sign on their iPhone without downloading anything?
Yes. When you send a document with Sign PDF, your client opens the email link in Safari, enters the six-digit code we email them, and signs with their finger. No account or app is needed.
Why does my signature look shaky on iPhone?
Signing small with a fingertip exaggerates every wobble. Turn the phone sideways for a wider box, sign larger and more slowly, then shrink the signature on the page.
Upload a document and watch the boxes land
See every signature, initial and date box placed before you sign up. Sending starts at $5 a month, monthly, cancel any time.
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