Protect PDF is a free tool that adds a password to a PDF, so only people who know it can open the document. It uses AES-256 encryption, which every modern PDF reader supports, and can also stop the document being printed, copied or edited. The PDF is encrypted in your browser, so the file and the password never leave your device.
How to password protect a PDF
- Choose your PDF.
- Type a password twice. Tick Show password to check it.
- Choose what people can do after opening it: print, copy text, or edit and fill forms.
- Click Protect and download, then open the new file to check the password works.
Choosing a good password
- Use at least 8 characters, or better, three or four random words such as
maple-orbit-lantern. - Don’t use the recipient’s name, date of birth or the document’s title.
- Send the password separately from the file, for example by text message when the PDF goes by email.
- Need a strong password? Make one with the Password Generator.
Opening password and restrictions
The password you choose is needed to open the file; that is the real protection. The print, copy and edit settings are extra rules that PDF apps follow once the file is open. They stop casual copying, but anyone who can read the document could still photograph the screen, so don’t rely on them for secrets.
Before you share it
A password hides the content, but the file name stays visible. PDFs also carry hidden details such as the author’s name; remove them first with the PDF Metadata Remover. To remove a password later, use Unlock PDF.
Frequently asked questions
How secure is the password protection?
The PDF is encrypted with AES-256, the strongest standard PDF encryption. Security then depends on the password: a long, unusual password can’t realistically be guessed, while a short common word can.
Will people be able to open it in any app?
Yes. Adobe Acrobat, Preview on Mac, Chrome, Edge, Firefox and phone PDF viewers all open AES-256 PDFs and ask for the password.
What if I forget the password?
The PDF can’t be opened without it, and it can’t be recovered: the password is never sent or stored anywhere. Keep a copy of the original, unprotected file somewhere safe.
Is my password sent anywhere?
No. The PDF is encrypted inside your browser, so neither the file nor the password leaves your device.
Do the print and copy restrictions always work?
Most PDF apps respect them, but they are instructions to the app, not strong protection. Anyone who can open the PDF could still take screenshots. The password to open the file is the real protection.
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