PDkefiPhoneOn-device
iPhone, right in Safari

How to Sign a PDF on iPhone for Free

You can sign a PDF on your iPhone without printing it or installing another app. Save the attachment to Files, open it in PDkef, add your answers and signature, then send it back. The signing is free and happens on your phone. Apple's own PDF tools are an option too.

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Four steps

Fill and sign a PDF in Safari on iPhone

  1. 1Save the attachment to Files. Open the PDF, tap Share, then Save to Files. Choose On My iPhone if you want a local folder rather than iCloud Drive.
  2. 2Open pdkef.com/sign in Safari. Tap to choose a file, choose Browse if needed, and select the PDF from the folder you just used.
  3. 3Fill it in, then add your signature. Place text and check marks where needed. Draw your signature with a finger, type it, or choose an image of a signature.
  4. 4Download the finished PDF. Look for the new file beginning with "signed_" in Files. If Safari opens a preview instead, use Share, then Save to Files. Open the saved copy and check every page before sending it.
Real PDkef editor showing the empty file picker with Drop PDF here
Open pdkef.com/sign and choose your file. There is no account or upload step; the PDF loads straight into the browser.
Real PDkef Create Signature dialog with Draw, Type, and Upload tabs
Draw, type, or upload a signature. Typed signatures use a handwriting font; drawn ones follow your finger.
Real PDkef editor showing a practice form filled in with text, a checked box, and a typed signature
The same document, filled in and signed. Text, a checked box, and a typed signature, all placed before download.
The WhatsApp form

How to sign a PDF sent through WhatsApp on iPhone

  1. 1Open the PDF in the WhatsApp chat. Tap Share, choose Save to Files, and pick a folder you can find again. Keep the original attachment as your starting copy.
  2. 2Choose the saved file in the signing tool. Fill in the requested details, add the date and signature, then download the new PDF.
  3. 3Send the signed copy back as a document. In WhatsApp, open the chat's attachment menu, choose Document, and browse to the new file in Files. Select the name beginning with "signed_" and check it before sending.

You can also use Share in PDkef when Safari supports it. Tap Share to prepare the finished PDF, then tap it again to open the share sheet and choose WhatsApp. If WhatsApp is not offered, save the PDF to Files and attach it from the chat. Sending the PDF keeps the full document together.

Apple tools, side by side

Signing with Files, Markup, or Preview on iPhone

Your iPhone already has useful PDF tools. Apple's form filling and Markup tools can add text and signatures, and AutoFill can use saved contact details in supported forms. On iOS 26, Preview also fills and signs PDFs. If those do what you need, use them. PDkef offers another workflow in Safari.

The available controls depend on your iOS version and the app opening the document.
What you need to doApple PDF toolsPDkef
Add a handwritten signatureAdd or reuse a signature with MarkupDraw, type, or choose a signature image
Complete a supported PDF formForm filling and AutoFillPlace text and check marks on the page
Add text to a flat or scanned formAdd and position a text form boxTap the page to add a text box
Mark a checkbox on a scanned formDraw a tick or place an X with MarkupPlace a check mark or cross
Useful beyond one signature

Free signing, with your PDF kept on your phone

There is no signup or watermark. PDkef processes the file locally and is open source under the MIT license. Your browser can keep a draft and saved signatures for next time. Where you save or share the finished document is your choice; selecting iCloud Drive or WhatsApp uses that service.

Need it without a connection? Install PDkef for offline use while connected, let its assets finish downloading, and test an export with your chosen font. If you need to remove personal details before sharing a copy, the PDF redaction tool can black them out before you send it.

Signing on a different device?

Sign a PDF on iPhone
Got questions?

Frequently asked questions

Do I need an App Store download to sign a PDF on iPhone?

No. PDkef runs in Safari with no account or subscription. Your iPhone also has built-in signing tools through Markup and, on iOS 26, Preview. A draft and saved signatures may remain locally in Safari for next time.

How do I sign a PDF file sent through WhatsApp on iPhone?

Open the attachment in WhatsApp, tap Share, and choose Save to Files. Select that PDF in PDkef, add your signature, and download it. Then attach the new file beginning with "signed_" as a Document in the WhatsApp chat. Do not forward the unsigned original.

Can I fill and sign the PDF with Apple's own tools instead?

Yes. Apple supports form filling, text boxes, AutoFill in compatible forms, and signatures through its PDF tools. Preview on iOS 26 also handles these tasks. The available controls depend on your iOS version and the document, so choose the tool that fits your form.

Does this work on iPad too?

Yes. Open PDkef in Safari on iPad and choose the PDF from Files. You can draw a signature with a finger or, on a compatible iPad, an Apple Pencil. Apple Pencil does not work with iPhone.

Where does Safari save my signed PDF?

Check Safari's Downloads and the Files app. The folder depends on your Safari download settings and can be in iCloud Drive or On My iPhone. If the PDF opens in a preview, tap Share and Save to Files to choose the folder yourself.

Can I sign offline on my iPhone?

Yes, once the app and required assets are available offline. Install while connected and test an export with your chosen font first. Keep the source PDF downloaded on the phone too. Sending the result through WhatsApp or email still needs a connection.

Can I type my signature instead of drawing with my finger?

Yes. You can type your name or choose an image of your signature. To improve a drawn signature, draw it larger and resize it on the page. Follow the recipient's instructions if they require a specific signature method or signing service.

Does PDkef update the PDF's interactive form fields?

It adds text, check marks, and signatures to the page rather than populating interactive field values. If the recipient requires the original form's fields or submit button to work, use a compatible form reader for that document.

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