Protect PDF

Protecting a PDF means encrypting it so that anyone opening the file must enter the correct password first. This tool adds that open-password (user-password) encryption directly in your browser, which is significant for security: your document and the password you choose never travel to a server, so there is no upload that could be intercepted or logged. The encryption scrambles the file's contents, not just a viewer setting, so the protection holds even if someone copies the raw bytes. There is a crucial distinction worth understanding. A user password controls whether the file opens at all, while an owner password governs permissions such as printing or editing once the file is already open. Owner-password restrictions are widely known to be weak, because many PDF readers honor them only by convention and can be told to ignore them. An open password is the meaningful protection, and that is what this tool sets. Encryption strength matters too: a long, unique passphrase resists brute force far better than a short word, because the math is only as strong as the secret behind it. Because there is no recovery mechanism by design, a forgotten password means a permanently inaccessible file, so store it in a password manager. Typical uses include locking contracts and NDAs before emailing them, securing tax documents and financial reports, and adding access control to HR records. If you later need to remove the password, the companion Unlock PDF tool does that when you supply the correct password. Everything runs locally, so even highly sensitive files stay on your device throughout the process.