Protecting a PDF means encrypting it so that it cannot be opened without the correct password. Doctor PDF applies real AES-256 encryption — the same standard banks use — not a fake lock that any tool can strip away. Once protected, the file's contents are genuinely scrambled, and anyone who receives it must enter the password to read it.
With Doctor PDF you choose a password, and the tool encrypts your PDF directly in your browser, producing a file that truly requires the password to open.
The encryption runs entirely inside your browser. Your file and your password are never uploaded to any server, so the sensitive document you are trying to protect never leaves your device in the first place.
This is real, strong AES-256 encryption performed locally — there is no limit on file size, and your password is never stored or transmitted anywhere.
Tired of ads, file limits, and uploading your documents to a stranger's server? Doctor PDF is built differently:
Yes. Doctor PDF adds real password encryption 100% free with no limits or sign-up.
Yes. Your file is encrypted with genuine AES-256 — the PDF truly requires the password to open.
For your security the password is never stored anywhere, so keep it safe — it cannot be recovered.
Yes. Everything runs locally in your browser — your files are never uploaded to any server.
Yes, on any modern browser — phone, tablet, or computer.