You’re about to email a payslip, a tax return or a scan of your passport. A password on the PDF means that if the email lands in the wrong inbox, or the file sits in a shared folder, nobody can read it without the password.
How to add a password
- Open the editor and choose your PDF.
- Next to Download, open More ways to save and pick With a password.
- Type the password, then type it again in Repeat the password.
- Click Download. The protected copy is saved under the same name.
That’s it. Anyone who opens the file, in Acrobat, Preview, Chrome, Edge or on a phone, is asked for the password first.
You can edit the PDF before you protect it: change text, sign it, fill its form. The protected copy includes all of it.
How strong is it?
The file is encrypted with AES-256, the strongest method PDFs support, and the same one Acrobat uses. Without the password the content is unreadable noise, not just hidden.
The password is only as strong as you make it. A short word can be guessed by a program that tries millions of them. Use a phrase of three or four words, or a mix of letters, numbers and symbols, at least 12 characters long.
Send the password another way
If you send the file by email, don’t put the password in the same email. Text it, say it on the phone, or send it in a different app. Otherwise anyone who gets the email gets both.
Keep the password safe
There’s no “forgot password” for a PDF. The password isn’t stored anywhere, so nobody can recover it for you, us included. Save it in your password manager before you send the file.
Why do it in the browser?
Most online tools that add a password upload your file to their server first, so the unprotected PDF passes through someone else’s computer. That is exactly what you’re trying to avoid.
Here the encryption happens on your device. The PDF is never sent anywhere, before or after it’s locked.