What happens if I forget the password?

The document is gone. No copy of the password is kept anywhere, and AES-256 has no back door.

Where does my password go?

Into this tab’s memory and nowhere else. qpdf is compiled to WebAssembly and runs inside the page, so neither the document nor the password you type ever becomes part of a request.

It says my PDF is already encrypted. Now what?

qpdf has to decrypt a document before it can re-encrypt it, and this tool never asks for an existing password. A file carrying only owner restrictions still opens, so protecting it works and replaces those restrictions with yours. A file with an open password will fail until that password is removed, run it through Remove PDF Password, which needs the password you open it with, then come back.

Why was my password rejected for starting with a dash?

qpdf takes its instructions as command-line arguments, and a leading dash reads as one of them.

Protect PDF

No upload · runs in your browser

Drop a PDF to protectYou’ll set the password on the next stepSelect PDF No upload · processed locally · auto-deleted

Encrypted in your browser , the file and the password are never uploaded.

How it works

Password protect a PDF with AES-256

Lock a PDF with a password using AES-256 encryption, and optionally stop it being printed or copied. The document and the password are handled entirely in your browser.

What this does

AES-256 encryption applied by qpdf, the strongest key length the format defines
The password you set is the open password, no reader gets past it without one
One switch clears the print, copy, edit and annotate permission flags
Turning restrictions on mints a random owner password you never see, so your own password cannot lift them
Reads the file first and warns you if it is already encrypted
Strength read-out on the password as you type it

FAQ

No. Those are permission flags, an instruction to the viewer, not a lock. Acrobat and Preview honour them; plenty of libraries read straight past them, and many tools strip them in a single pass. The password is the part that is real: under AES-256 the page content is genuinely encrypted and unreadable without the key. Treat the password as the security and the restrictions as a polite request. Switching restrictions on also generates a random owner password, so the password you hand out cannot be used to lift them.

Keep going

Bates Numbering

Compress PDF to Size

Extract PDF Pages

Extract Images from PDF

Grayscale PDF

Markdown to PDF