Can anyone open the locked PDF without the password?
No. The file is encrypted using standard 128-bit cryptography. Any viewer will refuse to display the contents without the correct password.
Encrypt your PDF with strong 128-bit / 256-bit password protection online free. Prevent unauthorized opening, copying, or printing of private documents.
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🚀 Open 🔒 Lock PDF (Protect)Whether you are sharing financial disclosures, employee contracts, or personal legal records, password protection is your first line of defense. Without encryption, an attachment can easily be forwarded or leaked.
SmallPDF Pro allows you to lock any PDF document directly inside your web browser. You do not need to install costly commercial software or trust an external cloud service with your private records.
Simply choose a strong password, optionally disable printing and text extraction, and export your protected PDF with standard 128-bit encryption that works across all devices.
Drag your PDF file into the drop zone or choose it from your file browser.
Type the password recipients will need to open the document. The built-in strength meter helps ensure strong protection.
Optionally check "Prevent printing" or "Prevent copying text/graphics" to lock down permissions.
Click "Lock PDF". Your file is encrypted instantly in browser memory and saved to your device.
No. The file is encrypted using standard 128-bit cryptography. Any viewer will refuse to display the contents without the correct password.
Because encryption happens locally on your computer with zero server logging, neither we nor anyone else has a backup copy of your password. Always make a note of your password in a secure password manager.