How to Password Protect a PDF for Free

2026-02-20

Sending a confidential PDF by email without protection is like mailing a postcard. Anyone who intercepts it can read everything. Password protecting your PDF adds a layer of encryption that ensures only the intended recipient can open the file. The good news is that you do not need Adobe Acrobat or any paid software to do this.

Two Types of PDF Passwords

PDFs support two distinct types of password protection. A user password (also called an open password) prevents anyone from opening the file without entering the correct password. An owner password (also called a permissions password) allows the file to be opened but restricts actions like printing, copying text, or editing. For genuine security, always use a user password with strong encryption. Owner passwords can be bypassed with freely available tools and provide only a thin deterrent.

How to Add a Password to a PDF

Using Luleit's PDF protection tool, open your file in the browser, enter a strong password, and download the encrypted version. The tool applies AES-256 encryption, which is the same standard used by governments and financial institutions. Because the encryption happens entirely in your browser, the unprotected version of your document never travels over the internet and never touches a remote server.

Choosing a Strong Password

Your PDF encryption is only as strong as your password. Avoid short, dictionary-based passwords like names, dates, or common words. A strong password should be at least 12 characters and include a mix of uppercase and lowercase letters, numbers, and symbols. Consider using a passphrase, a sequence of random words that is easy to remember but hard to guess, such as 'correct horse battery staple.' Never send the password in the same email as the PDF. Use a separate channel like a text message or phone call.

When to Password Protect a PDF

Use password protection whenever you are sharing sensitive information electronically. This includes tax returns, financial statements, legal contracts, medical records, employee documents, and any file containing personal identifiable information. Even if you trust the recipient, emails can be forwarded, accounts can be compromised, and devices can be lost. Encryption ensures the content stays protected regardless of where the file ends up.

Limitations to Keep in Mind

Password protection encrypts the file contents, but it does not prevent someone who knows the password from sharing the decrypted file with others. It also does not protect metadata like the file name, page count, or file size, which remain visible without the password. For maximum security, combine password protection with secure file transfer methods and communicate passwords through a separate channel.