PDF Kite

Password protect a PDF

Add a password to a PDF so only people who know it can open the file. The PDF is encrypted in your browser, so neither the file nor the password is sent anywhere.

Runs in your browser. Your files never leave your device.

How to use it

  1. Choose the PDF to protect.
  2. Type a password twice, and untick anything people shouldn't do after opening it: print, copy text, or edit.
  3. Press “Protect PDF” and send the protected file. Share the password separately.

How the password protection works

The PDF is encrypted with AES-256, the strongest method the PDF format offers and the one Acrobat uses by default. Without the password the file can't be opened at all: the content is scrambled, not just hidden behind a prompt.

The print, copy and edit settings are a separate layer that well-behaved PDF apps respect once the file is open. They stop casual copying, but they're honoured by the app rather than enforced by encryption.

Choosing a password

Use a passphrase of four or more unrelated words, or a long password from a password manager. Send it by a different route than the PDF itself, for example by text message when the PDF goes by email.

FAQ

What if I forget the password?

There's no way back in. Nothing is stored here, so keep the original unprotected PDF or keep the password somewhere safe.

Will it open on every device?

Yes. AES-256 PDFs open in Acrobat Reader, Preview on Mac, Chrome, Edge, Firefox and phone PDF viewers from the last decade.

How do I remove the password later?

Open the file in Unlock PDF and type the password; you'll get a copy without it.

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