Protect PDF
Add a password to a PDF with AES-256 encryption.
About this tool
Protect PDF locks a PDF with a password so only people who know it can open the file. It uses AES-256 encryption, the strongest option in the PDF standard, and lets you allow or block printing, copying and editing. Your files are processed on your own device. Nothing is uploaded to our servers.
How to use Protect PDF
- Choose the PDF you want to lock.
- Type a password twice and pick what readers may do.
- Press “Protect PDF” and download the encrypted file.
Questions people ask
How strong is the protection?
The file is encrypted with AES-256, the method defined in PDF 2.0. A long password (12 or more characters mixing words and numbers) cannot realistically be guessed. Short or common passwords can be cracked, so pick a strong one.
What if I forget the password?
There is no recovery. We never see or store your password, and the encryption has no back door. Keep the original unprotected file or save the password in a password manager.
Will the PDF open in any reader?
AES-256 is supported by Adobe Acrobat and Reader (version X and later), Chrome, Edge, Firefox, macOS Preview and current mobile readers. Very old readers from before 2010 may not open it.