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Client-side · No uploads · 100% Private

Protect PDF

Add a password to your PDF to restrict access — entirely in your browser.

Required to open the PDF.

Controls editing/printing permissions. Defaults to the user password if left blank.

🔒 Encryption note: pdf-lib uses RC4 40-bit encryption — the same standard used by most desktop PDF tools for basic password protection. For maximum security, use a strong, unique password.

All processing happens in a Web Worker thread inside your browser. Your files and passwords never leave your device.

What is the Protect PDF tool?

The Protect PDF tool secures your sensitive documents by locking them with a strong password. You may have a file containing financial records, legal agreements, or personal diary details that no one else should see.

Applying a password means you safely lock out any unauthorized person trying to open, print, or copy from your file. Your PDF becomes encrypted, offering you true peace of mind.

How to Password Protect PDF for Free (Step-by-Step)

Here is how you can lock up your sensitive files:

  1. Pick your document: Upload the PDF file onto the locking workspace.
  2. Create a secure password: Type in a strong password that you will use to open the file later.
  3. Confirm your password: Retype your password to make absolutely sure there are no typos.
  4. Encrypt and save: Push the protect button, and then download your securely locked file.

Why Processing Locally is Safer for Your Files

Putting a password on a document through a generic website means your unencrypted file is temporarily exposed on their server. PDFSetu handles this locally. Your files are processed inside your web browser (Client-Side), so everything remains 100% private.

There are no server uploads, no data retention, and zero risk to your privacy. This encryption is processed fast on your own device and is completely free.

Frequently Asked Questions (FAQs)

  • What happens if I forget the password?
    Because we encrypt your file right in your browser without saving any data, we cannot recover forgotten passwords. Please keep your password saved safely somewhere!
  • Can a hacker steal my PDF while it encrypts?
    No. Your document is never uploaded across the internet. It goes straight from your hard drive into the browser cache to be locked locally.
  • Is it free to put a password on my file?
    We believe privacy is a right. The Protect PDF tool is completely free for everyone.