What does this tool do?
It encrypts a PDF with a password of your choice. Anyone who tries to open the protected file — in a browser, in Acrobat, on a phone — is asked for that password first, and without it the contents are unreadable. You can also set permission flags that ask viewers to block printing, copying text, or modifying the document for people who open it.
How to password-protect a PDF
- Add the PDF you want to lock.
- Type a password twice — the tool checks that both entries match so a typo can't lock you out.
- Optionally untick printing, copying or modifying to restrict what readers can do.
- Click protect and download the encrypted file. Test it once before sending: opening it should demand the password.
What the encryption actually protects
The document's contents are encrypted with a key derived from your password, so the protection travels with the file — email attachments, USB sticks and cloud copies all stay locked. One nuance worth knowing: the open password is strong protection, while the permission flags (no printing, no copying) are honored by well-behaved PDF viewers rather than enforced by mathematics. Treat permissions as a strong request, and the password as the real lock.
Encrypted on your device
Sites that password-protect PDFs usually receive your unprotected file on their servers first — exactly the thing you were trying to avoid. Here the encryption runs inside your browser: the unprotected original never crosses the network, and neither does your password. There's nothing to trust and nothing to delete afterwards.
Tips
- There is no recovery if you forget the password — that's the point of encryption. Store it in a password manager.
- Use a real password, not the recipient's name or "1234"; short guessable passwords can be brute-forced.
- Need to remove protection later? The Unlock PDF tool on this site does it in seconds, as long as you know the password.