Add Password to PDF
Protect PDF with password encryption and permissions.
Drag & drop files here, or click to select
How to Protect PDF Files With Password Online
Select the PDF file from your device.
Enter your open password or owner password.
Set the permission checkboxes for printing, editing, or copying.
Click the Add Password button to encrypt and save your file.
Why Use SonuPDF to Protect PDFs?
Client-Side Encryption
Processing is fully in-browser. In contrast to online upload tools, your password and files never leave your computer.
Custom Permissions
Control who can print, copy text, or modify your PDF document settings.
Strong Encryption
Uses secure standard PDF encryption algorithms to safeguard your files from unauthorized viewing.
Completely Free
Secure any number of documents without upload limits or monthly charges.
Frequently Asked Questions
Yes, the encryption is processed entirely inside your browser locally. No data or password keys are sent to our servers.
A user password is required to open the PDF. An owner password protects permissions such as printing, copying text, or editing.
No. Because we do not store or process your documents or passwords on our servers, it is impossible for us to recover forgotten passwords. Keep them written down safely.
Yes, all standard PDF viewers, including Adobe Acrobat, web browsers, and mobile readers, will prompt you for the password correctly.