How-to

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

Your iPhone can already sign a PDF with no extra app: open it in Files or Mail, tap the Markup icon, add your signature with the + button, and save. It takes under a minute and works completely offline.

Sign it yourself, right now (built into iOS)

1. Open the PDF. In the Files app, tap it to open. From an email, tap the PDF attachment to preview it.
2. Tap the Markup icon. It's the pen-tip-in-a-circle icon — in Files it's in the top-right toolbar; in Mail's preview, tap the thumbnail first, then look for Markup in the menu that appears.
3. Tap the + button, then Signature. If you've signed on this iPhone before, your saved signature appears — tap it to insert. Otherwise, sign with your finger on the line that appears and tap Done to save it.
4. Drag it onto the signature line. Use the blue resize handles at the corners to size it to fit, the same way you'd resize a photo.
5. Tap Done. In Files, this saves the signature directly into the PDF in place. From Mail, tap Done again, and you'll be asked whether to save a copy or attach the signed version to a reply.

Common mistakes

• Signing the wrong copy. If you opened the PDF from a Messages thread or a downloads folder, check where Markup actually saved the signed version before assuming it's the one you'll send back.
• A signature too large or crooked to look real. Take a second pass at resizing — a signature that overflows the line reads as sloppy on a document someone else has to accept.
• Using this for someone else's signature. Markup only signs a copy sitting on your own phone. It doesn't send anything, collect a signature from someone else, or keep a record of who signed and when — see below for when that actually matters.

When Markup isn't enough

Markup is genuinely the right tool when you're the only one signing and you just need to get your own signature onto a document you already have. It stops being enough the moment you need someone else's signature — a client accepting a proposal, a vendor countersigning an agreement — because Markup has no way to send the document out, know whether the other person actually opened it, or prove when and how they signed.

That's the gap a tool like DocuAgree fills: you build or upload the document once, add the other person's email, and they get a link to sign from their own phone — no app, no account required on their end either. You get a certificate of completion and an audit trail the moment they finish, which a Markup signature alone doesn't give you.

General guidance based on iOS's current Markup behavior — Apple can change where these controls live in a future update.