Password Protect Your PDF Online Free
Encrypt a PDF with a password so only intended readers can open it.
How to Password Protect a PDF in 3 Steps
- Upload your PDF. Drag and drop or browse for the PDF you want to protect with a password. Any PDF up to 50MB is supported.
- Enter a password. Type a strong password for your document. Choose a password with at least 8 characters including letters and numbers. You will need this password to open the protected PDF.
- Download your protected PDF. Click "Protect PDF" and download your encrypted document. Anyone who tries to open this PDF will be prompted to enter the password you set.
Why Use PDFTools to Protect PDF?
- 256-bit AES encryption — PDFTools uses 256-bit AES encryption — the same standard used by governments and financial institutions — to protect your PDF with a password.
- Password required to open — The encrypted PDF cannot be opened, viewed, or printed without the correct password. The content is completely inaccessible to anyone without it.
- Universal compatibility — Password-protected PDFs work in Adobe Acrobat Reader, Preview on Mac, and all other standard PDF viewers. Recipients will be prompted for the password when they try to open the file.
- Secure and private — PDFTools does not store your password or the contents of your document. Files and passwords are deleted automatically after processing.
Frequently Asked Questions
How strong should my PDF password be?
Use a password of at least 8 characters, combining uppercase and lowercase letters, numbers, and ideally a special character. Avoid using simple words or sequences that are easy to guess. The 256-bit AES encryption used by PDFTools is extremely strong — a weak password is the most common vulnerability.
What happens if I forget the password?
PDFTools does not store your password and cannot recover it. If you forget the password to a protected PDF, the document cannot be opened. Always keep a record of your password in a secure password manager and retain an unprotected copy of the original if needed.
Can I protect a PDF that already has a password?
You would need to remove the existing password first using the Unlock PDF tool, then apply a new password using this Protect PDF tool. Processing an already-protected PDF without first unlocking it will result in an error.