Protect PDF: Free Online PDF Password Protector
Add password protection to your PDF documents to prevent unauthorized access — 100% private, all in your browser.
Securing your sensitive PDF documents is essential for protecting confidential information, financial data, and personal files. Our PDF protection tool allows you to add password security to any PDF document, ensuring only authorized users can view your content. Set a custom password, and your PDF will be encrypted with industry-standard security. The entire process happens locally in your browser — no files are uploaded to any server, ensuring your document and password remain completely private.
🔒 100% Client-Side Processing
🔐 AES 128-bit Encryption
📄 Password Protect PDFs
🛡️ Prevent Unauthorized Access
⚡ Instant Protection
💾 Download Secured PDF
🆓 Completely Free
💡 How it works: Upload your PDF, enter a strong password, and click "Protect PDF". A new password-protected PDF will be generated with AES encryption. Anyone trying to open the file will need the password you set.
🔐 Security Note: We use PDF encryption standards (AES 128-bit) to secure your documents. Choose a strong, unique password. The encryption happens locally in your browser — we never see your password or document content.
⚠️ Important: Store your password securely. If you lose the password, the PDF cannot be recovered or unlocked without the password. There is no password recovery feature for security reasons.
🔒 Protect PDF - Add Password Security
📄 Upload a PDF and set a password to prevent unauthorized access.
or drag & drop a PDF file here
Frequently Asked Questions about PDF Protection
How does PDF password protection work?
We use PDF encryption standards (AES 128-bit) to secure your document. When you set a password, the PDF is encrypted, and the password is required to decrypt and view the content. The encryption happens entirely in your browser using pdf-lib, ensuring your password never leaves your device.
What happens if I forget the password?
If you forget the password, the PDF cannot be recovered. This is by design for security — there is no backdoor or password recovery feature. We strongly recommend storing your passwords securely, such as using a password manager, and keeping a backup of the original unprotected PDF.
Is my document secure during protection?
Absolutely! The entire encryption process happens locally in your browser using pdf-lib. Your PDF and password never leave your computer — no uploads to any server. This ensures complete privacy for your sensitive documents and credentials.
What encryption standard is used?
We use AES 128-bit encryption, which is the industry standard for PDF security. This provides strong protection against unauthorized access while maintaining compatibility with all modern PDF readers like Adobe Acrobat, Preview, and browser-based PDF viewers.
Can I set permissions (printing, editing restrictions)?
This tool focuses on password protection (owner password) to prevent opening the document. For advanced permissions like restricting printing or editing, you would need professional PDF software. Our tool ensures only authorized users can view the document at all.
What makes a strong password?
A strong password should be at least 8-12 characters long, include uppercase and lowercase letters, numbers, and special symbols. Avoid common words, personal information, or sequential patterns. The password strength meter helps you gauge security.
Will this work on mobile devices?
Yes! The tool is fully responsive and works on smartphones and tablets. You can upload PDFs from your device, set a password, and download the protected version directly in your mobile browser.