How to password-protect a PDF before sharing it.

1. Finish editing before adding the password

Merge, organise or fill the document first, then open Protect PDF and choose the final unencrypted PDF. Most tools on this website need an unencrypted input. If you later need to change a protected copy, use Unlock PDF with a valid password and your permission, edit that copy and protect the finished version again.

2. Enter and confirm an opening password

Choose a long, unique password and enter it in both password fields. The tool requires at least eight characters; that minimum is not a promise that an eight-character password will be hard to guess. Store the password somewhere safe before continuing. PDF Toolbox cannot recover it, and neither the password nor the PDF is sent to our server.

3. Download the encrypted PDF

Choose Protect PDF. The browser runs qpdf locally to create an AES-256 encrypted copy. Keep the original in an appropriate location and check which version you intend to share. Only the downloaded protected copy receives the new encryption; other copies of the original do not change.

4. Test it in a compatible PDF reader

Open the protected download and confirm that it requests the password. Enter the password and check the pages. Some readers remember passwords during a session, so close the file or try a fresh reader session when checking whether a password is required. Confirm the recipient has a reader that supports the file before relying on it for a time-sensitive task.

5. Share the password separately

Send the encrypted PDF and communicate its password through a separate channel appropriate for the recipient. Anyone who obtains both can open it. On shared devices, remember that unencrypted originals, unlocked copies and downloaded files remain wherever you saved them.

What an opening password does not do

This tool protects access to the PDF with encryption. It does not verify a recipient’s identity, supply document tracking, prevent a person who can open the PDF from copying its contents, or provide separate printing and editing permission controls. A watermark is a visible page mark and does not provide password protection.

If you forget the password

The website has no stored password to return and the Unlock PDF tool does not guess passwords. Use the saved original to create a new protected copy if you still have it. If the file belongs to someone else, ask its owner for the password or an accessible version.