How to Password Protect a PDF Online Free

Protecting sensitive PDF documents with a password is essential for maintaining confidentiality. Whether you are sharing financial reports, legal contracts, medical records, or personal documents, adding password encryption ensures only authorized recipients can open them. Our free PDF password protector applies encryption directly in your browser.

How PDF Password Protection Works

PDF encryption uses AES-128 or AES-256 algorithms to scramble the file contents. Without the correct password, the file cannot be opened or read. There are two types of passwords: the user password (required to open the file) and the owner password (controls printing and editing permissions). Our tool sets both to the same password for maximum security.

How to Password Protect a PDF

1. Open the protector — Go to our Password Protect tool.
2. Upload your PDF — Select the document you want to encrypt.
3. Enter a password — Choose a strong password with letters, numbers, and symbols.
4. Download your protected PDF — The encrypted file requires the password to open.

Tips for Strong PDF Passwords

• Use at least 12 characters with a mix of uppercase, lowercase, numbers, and symbols
• Avoid common words, names, dates, or password123
• Never email the password in the same message as the PDF
• Share passwords through a separate channel (phone, SMS, or encrypted messaging)

If you need to remove password protection from a PDF, use our Unlock PDF tool. All encryption and decryption happens locally — your files never leave your device and no passwords are transmitted anywhere.