How to Sign a PDF on iPhone With Markup (Free)

Someone emails you a PDF, asks you to "sign and send it back," and you're nowhere near a computer. Good news: your iPhone has had a proper signature tool built in for years. It's called Markup, it's free, and once you know where it hides, signing a document takes under a minute.

Sign with Markup (built into iOS)

1. Open the PDF — from Mail, Messages, or the Files app.
2. Tap the Markup icon: the pen tip in the top corner (in Mail, tap the attachment first, then look for it).
3. Tap the + button, then Add Signature.
4. Sign with your finger. Take your time — the screen is small, but you can redo it as often as you like. Tap Done.
5. Drag the signature into position and resize it by the corner handles.
6. Tap Done, and iOS saves the signed copy. From Mail, it offers to attach it to a reply automatically, which is a genuinely nice touch.

Your signature is stored on the phone after the first time, so future documents are just + > Add Signature > pick it from the list. If you also need to fill in dates or checkboxes, the same + menu adds text boxes, and iOS 17's AutoFill can even detect form fields.

Where Markup falls short

Markup is great for the simple case, but a few things trip people up:

• Fillable form fields: PDFs with real interactive fields sometimes behave oddly in Markup — text lands beside the field instead of in it.
• Multi-page initialing: adding initials to twenty pages in Markup is slow, tap-heavy work.
• Neatness: finger-on-glass signatures look like finger-on-glass signatures. Some documents deserve better.

For those cases, open the PDF in Safari with our sign tool instead — it handles form fields properly, lets you place the same signature on many pages quickly, and you can draw the signature with more control (or type it in a script font if your finger refuses to cooperate).

A note on privacy

A signed document is, almost by definition, a sensitive one — contracts, leases, medical forms. Plenty of signing websites upload your document to their servers to process it. PeacefulPDF's sign tool doesn't: the PDF is processed on your phone, in the browser, and never leaves it. If you want to see the difference for yourself, our post on what happens when you upload a PDF shows how to check with airplane mode.

Signed. Now what?

If the file needs to go somewhere with a size limit, compress it first. And if you're curious whether a drawn signature actually counts legally (short answer: for most everyday documents, yes), we've unpacked that in electronic vs digital signatures.