← Scanlio

How to sign a PDF on iPhone, iPad and Mac

Scanlio scans paper, ID cards and passports into PDFs with automatic edge detection, recognizes text with multilingual OCR, lets you sign, annotate, white-out, merge and split PDFs, and converts PDF to Word, images or plain text; Scanlio Pro (a weekly, monthly or yearly subscription, or the one-time Lifetime purchase listed on the App Store) unlocks unlimited OCR, editing, signing, conversion and exports and removes ads.

Someone emails you a lease, a quote or a school form and asks for it back signed today. You do not need a printer. Every iPhone, iPad and Mac can sign a PDF, and the only real question is which tool gives you the cleanest result with the least friction. This guide walks through the three common options on Apple devices, then shows the full signing workflow in Scanlio, including the parts that other tools tend to leave out: dating the document, filling in names, and covering a wrong entry before you sign.

Three ways to sign a PDF on an iPhone

Apple Markup. Open a PDF in Files or from a Mail attachment, tap the pen icon, choose the signature tool and draw. It is free and built in. Markup is fine for a one-off signature, but it does not scan paper documents for you, has no white-out, and its text tool is basic. Apple documents the feature in its iPhone User Guide.
Adobe Scan plus Acrobat Reader. Adobe Scan captures the page; according to its App Store listing you then open the scan in the separate Acrobat Reader app to fill forms and sign. Two apps, and scans are saved automatically to Adobe Document Cloud.
Scanlio. One app scans the paper, recognizes the text, lets you sign with a stored signature, add text boxes and white-out, and exports the finished PDF. Nothing is uploaded, and no account is required.

Signing a PDF in Scanlio, step by step

Get the document into Scanlio. If it is on paper, tap the camera button and line it up; automatic edge detection crops the page and you can add more pages for a multi-page contract. If it arrived as a file, use the "+" menu to import the PDF or images from Files or Photos.
Open Markup. Open the document and choose Markup. This is where signatures, text boxes, highlights, freehand drawing and white-out all live.
Draw your signature once. Pick the signature tool and sign with your finger or, on iPad, with Apple Pencil. Scanlio keeps this as a reusable signature, so the next document takes a tap rather than another attempt at your handwriting.
Place and size it. Drag the signature onto the signature line, then resize it to fit the box. Landscape forms often have small signature fields; shrink the signature rather than letting it overlap the text.
Add the date and any names. Add a text box for the date, your printed name, or an initial in the margin. Text boxes in Scanlio can be moved, resized and recolored, so a dark blue "6 September 2026" next to a blue signature looks like it was written with the same pen.
Cover mistakes with white-out. If a field was pre-filled incorrectly, use white-out to cover the old text and type the correction in a text box over it. This is the step Markup alone cannot do.
Export and send. Save, then share as PDF via Mail, AirDrop, WhatsApp or any other app. The signed file is a normal PDF that opens anywhere.

Signing on iPad and Mac

Scanlio is a universal app. On iPad the same Markup tools work with Apple Pencil, which gives the most natural-looking signature of any method. On Mac (macOS 14 or later) you can import a PDF, place your saved signature, add text boxes and export, which is convenient when the document is already sitting in your Downloads folder. The Mac version of Scanlio shows no ads.

What makes a reusable signature useful

The first time you sign in an app, you spend a minute getting the strokes right. The value comes afterwards: a stored signature means the tenth form of the month is signed in seconds, and every copy of your signature looks identical. Because Scanlio keeps that signature on the device, it is available offline and never passes through a server.

Is an electronic signature valid?

In many jurisdictions, simple electronic signatures, a drawn signature placed on a document, are accepted for everyday paperwork: quotes, rental agreements, permission slips, consent forms, freelance contracts. Some documents, such as certain deeds, wills or regulated financial instruments, may require a specific type of signature or a witnessed process. If a document matters legally, check the requirements that apply to your country and to the document type. This page is general information, not legal advice.

Privacy: what happens to your signed document

Signing is usually the moment a document is most sensitive: it now contains your name, your signature and whatever the form asked for. Scanlio's privacy policy states that scanning, OCR, editing, conversion and storage happen locally on the device, and that Scanlio does not upload, collect, view or store the documents you create. There is no account to create and no cloud you are signed into by default. The file only leaves your device when you choose to share it, and it goes to the recipient you pick.

Free allowance and Scanlio Pro

Scanlio is free to download. E-signature is part of Scanlio Pro, and every tool shares the same free allowance, with saving never blocked. Pro unlocks e-signatures, the full PDF editor, unlimited OCR, format conversion and unlimited exports, and removes the non-personalized ads shown in the free iPhone and iPad version. Pro is available as a weekly, monthly or yearly subscription or as a one-time Lifetime purchase; prices are listed on the App Store at the time of writing and shown in your local currency on the purchase screen.

Common signing problems and fixes

The signature looks jagged. Sign larger than you need, then shrink it. Downscaling smooths the strokes; upscaling exaggerates them.
The form is a photo, not a PDF. Import the image into Scanlio; it becomes a PDF page you can sign and export like any scan.
The recipient wants the pages in a different order. Open Pages to reorder, rotate or delete pages, or merge several documents before signing.
You need the text of the contract as well. Use Convert to export to Word or plain text after signing; OCR keeps the document searchable.

Frequently asked questions

Can I sign a PDF on iPhone for free?

Yes. Apple's built-in Markup in Files and Mail can add a signature at no cost. Scanlio is free to download; e-signature is a Scanlio Pro feature that shares the app's free allowance, and Pro unlocks it without limits.

Do I have to redraw my signature every time in Scanlio?

No. You draw your signature once, with a finger or Apple Pencil, and Scanlio stores it as a reusable signature you can place on any document afterwards.

Is my signed document uploaded anywhere?

No. Scanlio signs, edits and exports entirely on your device. Your document and your stored signature are never sent to Scanlio's servers, and no account is needed.

Can I sign a PDF on my Mac with Scanlio?

Yes. Scanlio is a universal app for iPhone, iPad and Mac (macOS 14 or later), so you can import a PDF on the Mac, add your signature and text boxes, and export it.

Is a signature drawn in an app legally valid?

In many jurisdictions simple electronic signatures are accepted for everyday documents such as quotes, leases and consent forms. Regulated documents may require a specific type of signature; check the rules that apply to you. This is general information, not legal advice.

Download Scanlio free on the App Store

Related guides

Sources: Scanlio on the App Store (v1.0.17, 26 Aug 2026); Scanlio support page; Scanlio privacy policy; Apple: Fill out forms, sign documents and create signatures; Adobe Scan on the App Store. Prices are those listed on the US App Store on 6 September 2026 and can change.