Protect PDF

Password-protecting a PDF restricts who can open or modify it. This is essential when emailing sensitive material — financial statements, HR documents, private contracts — so that only people with the password can read it.

ColaPDF encrypts the document in your browser, letting you set a user password (to open the file) and an owner password (to change permissions). Because encryption happens locally, your unprotected file is never exposed on a server.

How it works

1. Upload your PDF
2. Enter a user password (required to open the PDF)
3. Optionally set an owner password to restrict editing
4. Click Protect PDF and download the encrypted file

Tips

• Store the password somewhere safe — a protected PDF cannot be opened without it.
• Share the password through a different channel than the file itself for better security.
• Use the Unlock tool later to remove protection if you know the password.

Frequently asked questions

What encryption standard is used?

Standard PDF encryption compatible with all modern PDF readers.

What if I forget the password?

There is no recovery — make sure to save your password somewhere safe.

Are files uploaded?

No. Encryption runs in your browser.

What permissions can I restrict?

Editing and copying are disabled by default. Printing and form filling remain allowed.