How to sign a PDF on a Mac or MacBook

The free way is already on your Mac: Preview can add a signature you draw on the trackpad, hold up to the camera on white paper, or write on your iPhone. When you need a photo of your real signature, your company seal, a PAID or APPROVED stamp, the same signature on every page, or a signed file small enough for an upload form, use 1Scanner for Mac. It is free, with no account and no ads, and the PDF never leaves your Mac.

Sign a PDF with Preview on Mac

Preview comes with macOS, so this costs nothing and needs no download. Apple describes the steps in its Preview guide:

1. Open the PDF in Preview and show the Markup tools.
2. Create a signature in one of three ways: sign with your finger on the trackpad, hold your signature on white paper up to the Mac's camera, or sign on a nearby iPhone or iPad.
3. Choose the signature, drag it into place and resize it.
4. Save. To keep the unsigned file, duplicate it first, because Preview edits the PDF you opened.

Apple says your Preview signatures are also available on your other Macs with iCloud Drive turned on. For a one-off form with one signature line, Preview is enough.

When Preview is not enough on a Mac

• A company seal or stamp. Apple's Preview guide describes three ways to create a signature: draw it on the trackpad, hold a signature on white paper up to the camera, or sign on a nearby iPhone or iPad. It does not describe adding a seal or a stamp.
• Many pages. Contracts often need initials on every page. In Preview you place each one by hand.
• Upload limits. A scanned contract with a signature can be several megabytes, while a portal accepts 1 or 2 MB. Preview can reduce a file's size, but you can't choose a target size.

Sign a PDF on Mac with 1Scanner: signature, initials and seal

1Scanner for Mac keeps a small library of your own signatures and stamps on the Mac, so you make each one once:

• From a photo or a scan. Sign a sheet of paper or stamp it with your company seal, photograph it, and add the picture. The paper is removed automatically and the image is cropped to the ink.
• With the iPhone camera. Take the photo with your iPhone straight into the Mac app (Continuity Camera).
• Drawn. Draw your signature or initials with the trackpad or the mouse.
• Ready stamps. APPROVED, PAID, COPY, CONFIDENTIAL, DRAFT, RECEIVED or a date, in red, blue or black, in the app's language, or a word of your own.

Step by step: sign a PDF on your MacBook with 1Scanner

1. Download 1Scanner for Mac and move it to Applications. It is signed with a Developer ID and notarized by Apple, so macOS opens it like any other app.
2. Make your signature, initials or seal once, from a photo, a scan, the iPhone camera or by drawing.
3. Open the PDF you need to sign.
4. Put the signature or a stamp on the page. Move, resize and turn it until it sits on the line.
5. For initials on every page, add it to all pages at once: it lands at the same spot on each page.
6. Save the signed PDF. It becomes a new file where you choose; your original stays as it was.

Make the signed Mac PDF fit an upload limit

If a website or an email accepts only a few megabytes, compress the signed copy in 1Scanner: pick a smaller preset or set a limit from 0.2 to 20 MB. The size of each choice is measured on your Mac before you save, so you know what you get. Text stays selectable. When a limit can only be met by turning pages into pictures, the app tells you that the text in that copy can't be selected or searched.

Is signing a PDF on Mac with 1Scanner private?

Yes. Signing and compressing run on your Mac, and documents are never uploaded. There is no account, no ads and no analytics or tracking. The app goes online only when you check for updates or install one. Your signatures and stamps stay in a library on the Mac. Details: 1Scanner for Mac privacy policy.

Not on your own Mac? The same kind of signing works in a browser on any computer without installing anything. On the phone, see how to sign a PDF on iPhone.

Is a PDF signed on a Mac legally valid?

Preview and 1Scanner both put a picture of your handwritten signature on the page, as if you had signed a printout and scanned it. That is not a certificate-based digital signature or a certified e-signature. Many forms, invoices and agreements only need a signed copy; when a bank, court or government office asks for a qualified e-signature, use the service it names.

Signing PDFs on Mac: questions