Protect PDF
Lock a PDF with an open password and AES-256 encryption, and optionally block printing, copying or editing — without the file ever leaving your browser.
How to Password-Protect a PDF in 3 Steps
Drop a PDF
The first page shows on the left so you know you have the right file.
Set the Password
Type the open password twice. In Settings you can add a separate owner password and untick anything you want to block — printing, copying, editing or commenting.
Protect & Download
Click Protect. The preview on the right is rendered from the encrypted file using your password, which proves it opens. Download and keep the password safe — it cannot be recovered.
Protect PDF — Frequently Asked Questions
How strong is the encryption?
AES-256 (PDF 2.0 standard security handler), the strongest level the PDF format defines. Any modern reader — Acrobat, Preview, Chrome, Firefox, Edge — opens it after the password.
What is the owner password for?
The open (user) password is what readers ask for. The owner password additionally unlocks the permission flags, so someone with only the open password cannot lift a printing or copying restriction. Leave it blank and a random one is used.
Do the permission restrictions really stop copying?
Honest readers obey them, and that covers most situations. They are flags, not cryptography — any tool that can open the file with the open password could ignore them. Treat them as a polite fence, and the open password as the real lock.
I forgot the password — can you remove it?
No. Nothing is stored and there is no back door; that is the point. Unlock PDF can remove a password you know, and can strip owner-only restrictions when there is no open password.
Is my PDF uploaded anywhere?
No. The document is parsed and rewritten by pdf-lib and rendered by PDF.js (the engine Firefox uses) entirely inside your browser. Nothing is transmitted or stored.