To password-protect a PDF on your phone, open Lock PDF in ProperPDF, pick the file, enter and confirm a password and save the protected copy. It runs offline on iPhone, iPad and Android. Lock and Unlock are Pro tools. ProperPDF can't recover a forgotten password, so keep the original or store the password safely.
| iPhone and iPad | Pro |
|---|---|
| Android | Pro |
| Works offline | Yes |
| Files uploaded | No, processing happens on the device |
| Account needed | No |
| Requires | iOS 17 or later on iPhone and iPad; Android 8.0 or later |
How to lock a PDF in ProperPDF
- Open ProperPDF and tap Lock/Unlock PDF.
- Select the PDF.
- Type a password and confirm it, or tap Generate Strong Password.
- Save. ProperPDF writes a protected copy.
- Open the copy and test the password before you send it.
Open passwords and restrictions
A full lock means nobody can open the PDF without the password. You can also set restrictions instead, which let people open the file but limit printing or editing in standard PDF viewers. Restrictions are easier to bypass with specialist tools than an open password.
Share the password separately
Send the PDF by email and the password by text message or a call. If both travel in the same thread, the lock does little.
Removing a password
If you know a PDF's password and want an unlocked copy, use Unlock in the same tool.
Questions
Can ProperPDF remove a password I don't know?
No. Unlock needs the current password.
Is locking a PDF free?
No. Lock and Unlock are part of ProperPDF Pro.