Encrypt a PDF
Short answer
Encrypt a PDF with AES-256 here — set a password and download the encrypted file. The encryption happens in your browser, so nothing is uploaded.
Choose a PDF to password-protect
or drop your file here.
Encrypted in your browser — nothing is uploaded
Runs in your browser — your file is never uploaded.
Encrypting a PDF scrambles its contents so that the pages are unreadable without the key derived from your password. That is a stronger guarantee than hiding a file or marking it confidential: someone who obtains the document still cannot read a word of it.
AES-256 is the strongest scheme the PDF specification defines and is what this tool uses by default. Because the encryption is genuine, it is also unforgiving — there is no recovery path if the password is lost, which is why the tool asks you to type it twice.
How to encrypt a PDF
- 1Add the PDF. Choose the document to encrypt.
- 2Set a password. Enter it twice to rule out a typo.
- 3Download. Save the AES-256 encrypted PDF.
Frequently asked questions
What encryption is used?+
AES-256 by default — the strongest the PDF format supports. 128-bit is offered for older readers.
Can the encryption be undone?+
Only with the password. Keep it safe; a lost password means the file cannot be opened again.