Lock PDF

Password-protect your PDF to prevent unauthorized access. Free and private.

📁

Drop your PDF here

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Accepted: .pdf · Max: 300 MB

About Lock PDF

Password-protecting a PDF is the simplest way to keep payslips, contracts, and personal records private in transit. Even if an email is forwarded or a drive link leaks, the file stays unreadable without the password.

This tool encrypts your PDF with a password entirely in the browser. The password never travels anywhere — the encryption happens on your device, which is exactly the property you want when the document is sensitive enough to lock.

How to use Lock PDF

1
Open the PDF
Load the document you want to protect.
2
Set a password
Choose a strong password — length matters more than symbols. It will be required to open the file.
3
Encrypt
The file is encrypted locally in your browser; the password is never transmitted.
4
Download and share safely
Send the locked file by any channel, and share the password separately (e.g. by phone).

Tips for better results

✓Send the password over a different channel than the file — that's what makes the protection meaningful.
✓There is no recovery if the password is lost, so keep an unlocked master copy somewhere safe.
✓Use a passphrase of several words: easier to read out over the phone, harder to crack.

Frequently Asked Questions

What kind of encryption is used? +

The PDF is encrypted with AES-256 (when supported) or RC4-128 bit encryption, which is the standard PDF security method.

Can I set different user and owner passwords? +

Yes. The user password is required to open the PDF. The owner password allows full control including removing the password.

What permissions can I restrict? +

You can restrict printing, copying text, and editing. The user can open and read the PDF but cannot perform restricted actions.

Will the password protect against all threats? +

PDF password protection is standard security, not unbreakable encryption. It deters casual access but is not a substitute for strong security measures.

Are my files private? +

Yes. All locking happens in your browser with pdf-lib. Your PDF and password never leave your device.