What Password Protection Actually Does
Protecting a PDF encrypts its contents so that only someone with the password can open and read it. This is genuine cryptographic security, not a visual deterrent: without the password the file is unreadable scrambled bytes, even to someone who has the file. It is the right tool for emailing a payslip, a bank statement, a contract or any document where the wrong recipient must not be able to read it. (If instead you only want a visible CONFIDENTIAL or DRAFT label across the pages, use the Watermark tool — that's cosmetic, not encryption.)
Encrypted Locally — How, and Why It Matters
The encryption runs entirely in your browser using an open-source library that implements the standard PDF AES encryption scheme. Your file and your chosen password are processed in local memory and the protected copy is assembled on your own device — there is no upload, so the unprotected document never crosses the network. The result opens in any standard PDF reader, which will prompt for the password before showing a single page.
One important consequence of doing this securely: there is no backdoor. If you forget the password, the file genuinely cannot be recovered — not by us, not by anyone. Choose something you'll remember, and share it with recipients through a separate channel (a phone call or message), never in the same email as the file.
Choosing a Strong Password
Use at least a dozen characters mixing words, numbers and punctuation, and avoid anything guessable like a name or date. For documents you send regularly to the same person, agree on a shared passphrase once rather than emailing a new password each time.