Encrypt PDF
Add a password to any PDF — standard AES-128 encryption. 100% in your browser.
Drop your PDF here
or click to browse · PDF only
Standard AES-128
Strong PDF encryption with broad reader compatibility.
100% Private
Your PDF never leaves your device. Encryption runs entirely in the browser.
Granular Permissions
Separately allow or forbid printing, copying, editing and annotating.
Frequently Asked Questions
What's the difference between open and owner passwords?
The open password is required to view the file. The owner password lets you change permissions (printing, copying, etc.) later. If you leave it blank, we reuse the open password.
What encryption is used?
PDFNinja uses standard AES-128 PDF encryption with your selected passwords and permissions. Choose a long, unique password to keep it secure.
Which PDF readers support this?
Standard AES-128 PDF encryption is supported by current Adobe Acrobat / Reader, macOS Preview, Chrome, Edge and most modern PDF apps.
Is anything uploaded?
No. Everything happens in your browser — the PDF never touches a server.
I forgot the password — can you recover it?
No, and neither can anyone else. Encryption is irreversible without the password. Store it in a password manager.