A PDF with no password can be opened by anyone who gets hold of the file - forwarded by mistake, left in a downloads folder, or intercepted somewhere along the way. For anything sensitive - identity documents, financial statements, signed agreements - adding a password is a small step that closes off a real risk.
What a PDF password actually protects
An "open" password (also called a user password) means the file simply won't open at all without it - the content is encrypted, not just hidden behind a prompt. That's different from just naming a file carefully or putting it in a locked folder; the protection travels with the file itself, wherever it ends up.
How to protect a PDF with a password, step by step
- Open the Protect PDF tool.
- Upload the PDF you want to lock.
- Set a password - something the recipient can be told separately (a text message or phone call, not the same email you're attaching the PDF to).
- Download the protected PDF and test it by opening it yourself first.
Picking a password that's actually useful
- Avoid anything guessable from the document itself - a birthdate on an ID document, for example, is a poor password for that same document
- Share the password through a different channel than the file itself, so intercepting one doesn't hand over both
- If you need to remove a password later - your own file, or one you're authorized to unlock - see the companion guide on removing a PDF password.