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How to password protect a PDF on iPhone

Before you email a payslip, a contract or a scan of your ID, you can add a password so only people you give it to can open the file.

We make PDF Tools Pro (method 2).

Method 1: Preview (free, iOS 26)

From Apple's guide to Preview on iPhone:

  1. Open the PDF in Preview.
  2. To keep an unprotected copy, tap next to the file name and tap Duplicate first.
  3. Tap next to the file name, then tap Lock.
  4. Enter the same password in Password and Verify. Require Password turns on automatically.
  5. Tap to apply.

Method 2: PDF Tools Pro (iOS 18 and later, on device)

  1. In Tools, tap Protect or Unlock PDF, then Protect PDF.
  2. Pick the PDF and enter a password.
  3. Save the protected copy. The app reopens it to check that it's locked, that your password opens it, and that no pages are missing.

The password is needed to open the new copy. Your original file isn't changed. Processing happens on your iPhone or iPad; nothing is uploaded. Protect is an advanced tool: three successful advanced outputs to try on each device, then Lifetime Pro is a one-time purchase, no subscription.

Download on the App Store

Core tools are free. Split, Extract and Protect/Unlock are advanced tools: three successful advanced outputs to try on each device, then Lifetime Pro is a one-time purchase. No subscription.

Tips for sending protected PDFs

  • Send the password a different way (for example, a text message if the PDF went by email).
  • Use a password you can share safely. There's no way to recover a forgotten PDF password.
  • Keep your own unprotected copy somewhere safe.

FAQ

Can I password protect a PDF on iPhone for free?
Yes, on iOS 26 with Apple's Preview app (Lock). PDF Tools Pro also gives three free advanced outputs per device (shared across tools).
Will the other person need an app to open it?
No special app. Any standard PDF viewer asks for the password.
Is my original file changed?
Not with PDF Tools Pro: it saves a new protected copy. In Preview, duplicate the file first if you want to keep an unprotected version.
Is anything uploaded?
No, not with the methods on this page.
What if I forget the password?
It can't be recovered. Keep an unprotected original.
How to Password Protect a PDF on iPhone (Offline)