Lock PDF with Password — Free Online
Lock your PDF with a password so only authorized people can open it. No upload, no signup — encryption runs completely in your browser. Free and private.
Lock your PDF so only people with the password can open it. Perfect for protecting contracts, tax documents, medical records, or any sensitive information you need to share securely via email or file transfer.
Drop PDF to password-protect
PDF • Max 200MB
How It Works
Add password protection to any PDF using AES-256 encryption — the industry standard used by banks and governments. The encryption process runs entirely in your browser using WebAssembly, so your PDF and password never leave your device.
Choose a strong password, confirm it, and download the encrypted PDF. Recipients will need the password to open the file. The original formatting, fonts, and images are preserved exactly.
Features
- ✓AES-256 encryption — military-grade security standard
- ✓Password-to-open protection prevents unauthorized access
- ✓Preserves all formatting, fonts, and embedded images
- ✓Handles PDFs up to 200MB
- ✓Zero-knowledge — your password never leaves your device
- ✓Compatible with all PDF readers (Adobe, Chrome, Preview)