PDF Password Protector
Add password protection to PDFs. Free, no signup, no upload.
How It Works
Select a PDF file and enter a password. Click Protect and the PDF is encrypted so that anyone opening it must enter the password first. No file is ever uploaded to a server.
Why Password Protect a PDF?
Password protection prevents unauthorized access to sensitive documents like contracts, financial statements, medical records, and confidential reports. The recipient must know the password to open and view the file.
When to Use It
- Emailing a contract, invoice, or bank statement to a client
- Sharing medical records or legal paperwork
- Sending payroll, tax, or HR documents
- Storing confidential files in cloud storage
- Distributing a report that only certain people should open
Share the password through a separate channel from the file itself — for example, send the PDF by email and the password by text message — so a single intercepted message never exposes both.
How Strong Is the Protection?
The tool applies 256-bit AES encryption, the same level used by Adobe Acrobat and trusted for confidential business documents. The strength of the protection ultimately rests on your password: a long, unique passphrase is far harder to guess than a short common word. You can create one with our Password Generator.
Frequently Asked Questions
How do I add a password to a PDF?
Select your PDF, type the password you want, and click Protect PDF. The tool encrypts the file and shows a Download button, saving it with a -protected suffix. Anyone who opens the file afterward, including you, must enter that password first.
What kind of encryption does it use?
It uses 256-bit AES encryption, applied by the qpdf engine. This is the strong, modern standard supported by Adobe Acrobat and other major PDF readers, so the protected file opens normally once the correct password is entered.
Are my files or passwords sent to a server?
No. The encryption runs entirely in your browser using qpdf compiled to WebAssembly. Your PDF and the password you choose never leave your device, are never uploaded, and are never stored anywhere.
Can I add a password to a PDF that is already protected?
No. If the PDF is already password-protected, encryption will fail. Remove the existing password first with our PDF Password Remover, then return here to set a new one.
What happens if I forget the password?
There is no recovery or back door. The password you set is the only way to open the file, so choose something strong but memorable and store it somewhere safe, such as a password manager. Without it the PDF cannot be opened.