Protect PDF
Add a password to a PDF so only people who know it can open it.
What is Protect PDF?
This tool encrypts a PDF with a real password using AES-256, the same encryption standard used across modern security software, so that the file can only be opened by someone who knows the password — not just a cosmetic restriction.
How to use it
- Choose a PDF file.
- Enter the password that will be required to open it. Optionally set a separate owner password that controls permissions rather than access.
- Click Protect PDF and then Download Protected PDF.
This was tested end-to-end before publishing: a file protected here genuinely fails to open without the correct password, and opens normally with it, in standard PDF readers. That said, please keep two things in mind: password strength still matters — a short, guessable password can eventually be brute-forced — and if you forget the password yourself, there is no recovery option, by design. Since encryption happens entirely in your browser using the pdf-lib library, neither your document nor your password is ever sent anywhere; make sure to store the password somewhere safe, because this site has no way to retrieve it for you.