Protect PDF with Password Free Online
Add password encryption to your PDF documents in seconds. Restrict opening, printing, and editing. 100% secure and local.
Select or Drag a PDF File
Set a password to prevent unauthorized access. Local conversion guaranteed.
How It Works & Privacy
This tool uses AES-256 encryption via pdf-lib, running 100% locally in your browser. Your password and file are never transmitted to any server.
How to Password Protect a PDF Online for Free
Upload your PDF, set a user password (required to open), and optionally an owner password (required to edit or print). Click "Protect PDF" to download your encrypted document.
Frequently Asked Questions
What encryption level is used?
We apply 128-bit RC4 encryption (PDF standard). This is compatible with all modern PDF readers including Adobe Acrobat, Chrome, and macOS Preview.
What is the difference between user and owner password?
The user password is required to open and view the document. The owner password controls permissions like printing, copying text, and editing. If left blank, both will use the same password.