How to Password Protect a PDF Online

Password protection is the simplest way to keep a PDF private — whether you're emailing a contract, sharing financial statements, or sending an invoice. A password stops anyone who receives the file from opening it without the key.

The Protect PDF tool adds encryption straight to your PDF. You set a password and optionally restrict printing or copying. The file is encrypted locally in the browser — the password never touches a server.

To protect a PDF: open Protect PDF, upload your file, enter a strong password, and download the encrypted result. It takes under a minute.

Use a strong, unique password — a full passphrase is safer than a short one. Remember that password protection is only as strong as the password itself.

If you later need to open a file someone protected, or you want to remove your own password, the Unlock PDF tool does the reverse — also locally and free.