Protect PDF files
Encrypt your PDF with a password. Unauthorized access is forbidden — only those with the password can open the document.
or drop PDFs here
How to protect pdf online free
Step 1
Use a strong password with mixed characters
Step 2
Store your password safely — we cannot recover it
Step 3
AES-128 encryption is applied by default
Frequently Asked Questions
Is this protect pdf tool free?
Yes, ThePDFNinja's protect pdf tool is 100% free to use. There are no hidden fees, subscriptions, or credit cards required.
How do I protect pdf for free?
Simply upload your document using the box above, configure any necessary options, and our servers will instantly process your file for free.
Do you store my files?
No. All files uploaded to ThePDFNinja are strictly confidential and are automatically and permanently deleted from our servers after 1 hour.
Does this work on Mac, iPhone, and Android?
Yes, as a web-based tool, it works flawlessly across all operating systems and devices, including Mac, Windows, iOS (iPhone/iPad), Android, and Linux.
Will there be a watermark on my file?
Absolutely not. We never add watermarks to your documents.
Why use ThePDFNinja to protect pdf?
ThePDFNinja provides the fastest, most reliable way to protect pdf online. Unlike other tools that force you to create accounts, pay subscription fees, or deal with heavy watermarks, our Protect PDF tool is completely free and accessible directly from your browser.
We prioritize your privacy above all else. Every document uploaded for protect pdf is processed in an isolated environment using AES-256 SSL encryption. Once your task is complete, the original and processed files are permanently deleted from our servers within 24 hours. We guarantee that your data is never read, analyzed, or shared with third parties.
Whether you are working from a desktop PC, a Mac, or a mobile device, you can easily protect pdf anywhere, anytime, without installing any software.