Drop a file here or click to choose
Your file stays on your device. Processing happens locally in your browser.
What is Protect PDF?
Protect PDF encrypts a PDF with AES-256 so it can't be opened without the password. Encryption happens in your browser, so neither the file nor the password is sent anywhere. You can also limit printing, copying and editing with an optional owner password. Old, weak RC4 encryption is never used.
Lock PDF files with a password using AES-256, the strongest standard PDF encryption — never the old RC4. Encryption happens on your device, so neither the PDF nor the password is sent anywhere. Optional permissions can restrict printing, copying and editing.
Key features
- AES-256 encryption (never RC4)
- Password strength meter and confirmation
- Optional print, copy, edit and annotate limits
- Optional separate owner password
- Password kept in memory only, never sent or logged
- Runs in your browser — the PDF is never uploaded
Popular uses
- Email bank statements, payslips and tax papers safely
- Share contracts and ID scans with a password sent separately
- Store sensitive documents in cloud folders
Supported formats
Input: PDF. Output: AES-256 encrypted PDF.
Troubleshooting
- The PDF is already encrypted Open it with its current password first, or remove it with Unlock PDF, then protect it again.
- The page says the PDF is too large for this device Large PDFs have to fit in your browser's memory. Close other tabs, use a computer instead of a phone, or split the PDF into smaller parts first.
Also known as: Password protect PDF, Encrypt PDF, Lock PDF, Secure PDF.
How it works
- Choose a PDF; it opens on your device.
- Type and confirm a password; optionally limit printing, copying and editing.
- Encrypt and download the protected PDF.
FAQ
Which encryption is used?
AES-256, the strongest standard PDF encryption. Old RC4 encryption is never used.
Is my password sent anywhere?
No. Encryption happens in your browser; the password is never sent, stored or logged.
What if I forget the password?
Nobody can recover it, including us. Keep it somewhere safe.
Is my PDF uploaded?
No. The PDF is opened and processed in your browser; it never leaves your device.
How strong should the password be?
Use at least 12 characters, or four or more random words. Send it by a different channel than the PDF.
Do permission limits really stop copying?
They are honoured by standard PDF readers but are easy to bypass with some tools. Only the open password truly protects the content.