How to Sign a PDF on iPhone (Free, No App Needed)

Option 1: Markup in the Files app

This is the built-in way, and it works on any recent iPhone or iPad. On iOS 26 or later you can also open the PDF in the Preview app and sign it there.

1. Save the PDF to Files. If it came in a text or a web page, tap the Share button and choose “Save to Files.”
2. Open the Files app and tap the PDF.
3. Tap the Markup button (the pen tip, at the top or bottom of the screen depending on your iOS version).
4. Tap the “+” button and choose “Add Signature.” The first time, draw your signature with your finger and tap “Done.” Your iPhone saves it for next time.
5. Drag the signature into place and pinch or pull the corners to resize it. Use the “+” button again to add text such as your printed name or the date.
6. Tap “Done.” The signed version replaces the file in Files. Share it from there by email, text or AirDrop.

Tip: if you need to keep the unsigned original, duplicate the file first (press and hold › Duplicate).

Sign a PDF attachment in Mail

1. Open the email and tap the PDF attachment.
2. Tap the Markup button, then “+” › “Add Signature,” and place your signature.
3. Tap “Done.” Mail offers to reply with the marked-up document attached, ready to send back.

This is the quickest way to return a signed form someone emailed you. Be aware that it attaches a new copy; the original stays in the email.

Sign a paper document with your iPhone

If all you have is paper, turn it into a PDF first. In the Files app, tap the three dots (More) and choose “Scan Documents,” or use the Notes app. Point the camera at the page; the iPhone crops and straightens it. Save the scan, then sign it with Markup as above. You can also upload a photo of the paper directly to MultiDocs, which cleans it up so it looks scanned.

Option 2: MultiDocs in Safari (with an audit trail)

Markup is enough when nobody will question the signature. When the document matters (a lease, a contract, an estimate you're approving), you want a record of the signature. This is just as quick and also free.

1. Open multidocs.app/sign-pdf in Safari. No app, no account.
2. Tap “Choose document” and pick the PDF from Files, or a photo from your library. You can also scan the paper with the camera.
3. Choose “Just me” and tap “Add my signature.” Sign with your finger.
4. Tap the spot on the page where the signature goes. Add your name, the date or a checkbox if the form needs them.
5. Tap “Finish” and download the signed PDF to Files, or send it by email.

When only you sign, the document stays on your iPhone: it's processed in Safari and never uploaded. The last page carries a signature record with the date and time and the document's SHA-256 fingerprint, so anyone can later confirm at /verify that it hasn't been altered.

Get someone else to sign from your iPhone

Markup can't ask another person to sign; you'd have to send them the file and hope they know how to use their own phone. Instead:

1. Upload the document at Sign a PDF and choose “Other people” (or “Others and me” if you sign too).
2. Tap “Mark where they sign” and place the box. Add fields for their name, date or initials.
3. Enter their email or mobile number. With text or WhatsApp, your iPhone opens the message ready to send from your own number. Or copy the link.

They open the link, sign with a finger and you get the signed PDF by email with a certificate showing the email or phone it was sent to, the IP address, device, date and time. Up to 20 people can sign the same document. Free for 15 requests a month. More in send a document for signature by text.

Which option should you use?

Is a signature made on an iPhone valid?

Yes. The federal ESIGN Act defines an electronic signature as an electronic “sound, symbol, or process” adopted with the intent to sign (15 U.S.C. § 7006(5)). A signature drawn with your finger in Markup qualifies, and so does one made in Safari. What differs is the evidence. If the other side disputes it, Markup leaves you with a drawing; an audit trail shows where the link was sent, from which device it was opened and exactly when it was signed. More in are electronic signatures legally binding?

Troubleshooting

• No Markup button: the file may have opened in a preview inside another app. Save it to Files first and open it from there.
• The signature is too big or blurry: sign larger and more slowly, then shrink it with the corners.
• The PDF is locked or password-protected: Markup may not edit it. Ask the sender for an unlocked version.
• Wrong page: scroll to the page that needs the signature before tapping “+.”