Put a password on my PDF

When you need this

You are emailing a payslip, a contract or a medical letter and the inbox at the other end is shared, or you are sending it over WhatsApp where it will sit in somebody's gallery. A password means the file is useless to anyone who gets hold of it by accident.

How to use it

1. Open the PDF.
2. Choose a password. Something you will actually remember, or something you are storing properly — see passwords that work.
3. Save the locked copy, and tell the person who needs it what the password is by a different route from the file itself. Sending the document and the password in the same WhatsApp chat protects nobody.

What it does and does not do

• Nobody can recover this password. Not you, not us, not the person you send it to. There is no reset, no email link, no support line. That is what makes it worth anything. If you lose it, the document is gone.
• The encryption is done on your phone, and the password is never sent anywhere, so there is nothing for us to keep even if we wanted to.
• It stops the file being opened. It is not a watermark and it does not track who opens it. Once somebody has the password they have the document and can pass it on.
• Some old PDF readers struggle with encrypted files. If the person receiving it cannot open it on an ancient phone, that is usually the reason.

If something goes wrong

• You forgot the password. There is nothing to be done. This is not us being unhelpful — a password that can be recovered by the website is not protecting the file. Go back to whatever you made the PDF from.
• You need to take a password off instead. That is take the password off my PDF, and it needs the password that opens it.
• The recipient says it is corrupted. Ask them to open it in a current PDF reader or in Chrome rather than an old built-in viewer.