← All PDF tools

Protect PDF

Protect a PDF

Add password protection before you share a sensitive document. Encryption happens locally.

Runs in your browser. Your PDF stays on this device — nothing is uploaded for processing.

Open password

Recipients need the password to view the file.

Local encryption

Keys never travel to our servers.

Quick share prep

Protect, download, then send your own way.

Pair with Unlock

Use Unlock later if you need a clear copy again.

Use the tool

How it works

Encrypt before you send

pdf-lib encrypts the document with your password using browser-side crypto.

Three steps

  1. 1

    Load a PDF

    Choose the file to protect.

  2. 2

    Set a password

    Choose a strong open password.

  3. 3

    Download

    Save the encrypted PDF.