Protect PDF
Secure your PDF documents with industry-standard AES-256 password encryption. Protect confidential files from unauthorized viewing with encryption executed completely inside your browser.
Your files never leave your device. All processing happens locally in your browser with no file uploads or account required.
How to use protect pdf
- 01
Choose a PDF
Select the PDF file you wish to encrypt with a password.
- 02
Set a strong password
Enter and confirm your chosen opening password. AES-256 encryption is applied in a dedicated local worker.
- 03
Download encrypted PDF
Save the protected PDF to your device. The document will require the password each time it is opened.
Important details & limitations
Choose a strong password and keep it somewhere safe. AES-256 encryption runs in a local worker. This tool does not add printing or copying restrictions.
Frequently asked questions
What should I know before using protect pdf?+
Choose a strong password and keep it somewhere safe. AES-256 encryption runs in a local worker. This tool does not add printing or copying restrictions.
Where are my files processed?+
All document contents remain on your device. Browser JavaScript and WebAssembly perform the work; no files are sent to a conversion service.
What files does protect pdf support?+
Use unencrypted PDFs; Unlock PDF can first remove encryption using a known password. Up to 100 MB total. Malformed, unusually large, or complex PDFs may exceed browser limits. Editing a signed PDF changes the document and can invalidate its signature.