Password Protect PDF Online — Free & Secure
Add password encryption to your PDFs with granular permissions. Protect sensitive documents from unauthorized access — all processing happens locally in your browser.
Why Choose Our PDF Password Protector?
Maximum Security
Your unprotected PDF never leaves your device. Cloud-based tools require uploading your sensitive document to remote servers — a major security risk. LocalPDF encrypts locally.
Granular Permissions
Set user and owner passwords separately. Control printing, copying, editing, and annotation permissions with industry-standard PDF encryption.
AES-256 Encryption
Uses the same encryption standard as military and banking applications. Your protected PDF is secure against brute-force attacks.
No Password Storage
We never see or store your password. Only you know the encryption key, ensuring complete confidentiality.
Works Offline
Once loaded, protect PDFs without internet. Perfect for confidential documents that shouldn't be transmitted over networks.
Instant Encryption
No upload time, no processing queues. Encryption happens in your browser at native speed — usually under 2 seconds.
Key Features
How It Works
100% Private Sandbox: Your files never leave your device. All processing happens locally in your browser's secure memory.
Frequently Asked Questions
What encryption standard is used?
We use laboratory-grade **AES-256 bit encryption**, which is the current standard for high-security applications worldwide. Your document is encrypted directly in your browser using the browser's native cryptographic APIs.
What is the difference between User and Owner passwords?
The **User Password** (Open Password) is required to view the document. The **Owner Password** (Permissions Password) is required to change security settings or override usage restrictions like printing or copying text.
Can I recover a forgotten password?
No. Since LocalPDF processing is entirely local and we do not store your passwords or documents, there is no way for us to recover a forgotten password. Please ensure you keep your passwords secure.
Are my passwords sent to a server?
No. Your passwords never leave your browser. They are used locally to generate the encryption keys needed to secure your PDF file in your device's memory.
Technical Architecture: How it Works
Zero-Knowledge Architecture
Our system is designed so that your data is never seen by anyone else. Processing happens in the browser's secure memory space.
WebAssembly Performance
We use high-performance WebAssembly modules to achieve desktop-grade PDF processing speeds directly in your web browser.