Protect PDF

Add a password to your PDF so only people who know it can open the file. Encrypted locally.

How to use this tool

Drop the PDF.
Enter a strong password.
Re-type it to confirm.
Click Protect and download the encrypted PDF.

How it works

PDF-lib re-saves the document wrapped in a standard AES-128 encrypted PDF, which any modern reader can open with the password.

Tips

Use a long passphrase rather than a short word.
Test the protected file by opening it once.

Limitations

Encryption restricts who can open the file; someone with the password can remove it. It does not prevent screenshots.

Frequently asked questions

Is the encryption strong?

The tool uses PDF-lib's standard PDF encryption (AES-128). That's sufficient for most personal and business documents.

What if I forget the password?

We can't recover it — store your password somewhere safe.

Can I also restrict printing?

The primary feature is requiring a password to open; some readers also honor permission flags.