Password protect PDF
online.
Add a password to any PDF — AES-256 by default. Encryption runs inside your browser, so the file and password never leave your device.
Three steps. Password never leaves this tab.
Drop your PDF
Pick the file you want to lock. It loads into your browser's memory, not a server.
Choose a password
Set a password and encryption strength (AES-256, AES-128, or RC4-40 for legacy).
Download protected copy
Anyone opening the file will need the password. Your original file stays untouched.
Frequently asked
Is my PDF or password sent to your server?
No. Encryption runs entirely in your browser using qpdf compiled to WebAssembly. The file and password never leave this tab — verifiable in DevTools → Network.
What encryption strength is used?
AES-256 by default — the strongest level in the PDF spec. AES-128 and RC4-40 are available for compatibility with older PDF readers.
Can I unlock a PDF I previously protected here?
Yes. Use the Unlock PDF tool with the same password. It uses the same engine.
What if I forget the password?
It cannot be recovered — by design. Always store passwords in a password manager.