Protect PDF

Add password protection to a PDF. Choose AES-256, AES-128, or RC4-40 encryption. Your files never leave your device.

Private by design

Your files never leave your device. All processing happens locally in your browser — no uploads, no servers.

Encryption is temporarily unavailable in this browser build: the bundled qpdf WASM has no crypto provider, so encrypting a PDF currently fails. An upgraded build is planned.

Drop your PDF here

or click to choose a file

Your files never leave your device.

User password (required to open)

Encryption strength

Set a separate owner password (optional)

Adds password encryption to your PDF. The password is required to open the document.

Protect PDF adds password encryption to your PDF so only authorized users can open it. Choose AES-256 (recommended, strongest), AES-128, or RC4-40 (legacy). You can set a user password (required to open) and an optional owner password (required to change permissions). Encryption runs entirely in your browser via qpdf-wasm — your file and password never leave your device.

How it works

How to use Protect PDF

1
Drop your PDF. Drag and drop a PDF file onto the drop zone, or click to choose a file from your device.
2
Choose a password. Enter a user password (required to open the document). Optionally set a separate owner password for permissions control.
3
Select encryption strength. AES-256 is recommended for modern viewers. AES-128 and RC4-40 are available for compatibility with older software.
4
Click Run Protect PDF. The tool encrypts your PDF locally in a Web Worker using qpdf-wasm. Your file and password never leave your device.
5
Download the protected PDF. The encrypted PDF is offered as a download. You will need the password to open it.

Features

What this tool does

AES-256 encryption (recommended, strongest)
AES-128 and RC4-40 for legacy compatibility
Separate user and owner passwords
No upload — runs entirely in your browser

Limitations

Things to know

You must remember the password — there is no recovery option
RC4-40 is weak and should only be used for legacy compatibility
Encryption does not redact content; it only restricts opening

FAQ

Frequently asked questions

Is my file or password uploaded anywhere?

No. Encryption happens entirely in your browser using a Web Worker and qpdf-wasm. Your file and password never leave your device.

What is the difference between user and owner passwords?

A user password is required to open the PDF. An owner password is required to change permissions (such as printing, copying, or editing). A PDF can have either or both.

Which encryption strength should I choose?

AES-256 is recommended for modern PDF viewers — it is the strongest and most secure. Use AES-128 or RC4-40 only if you need compatibility with older software that does not support AES-256.

Can I recover a forgotten password?

No. There is no password recovery. Please store your password in a safe place — without it, the protected PDF cannot be opened.