Free PDF Password Protector
Add a password so only people who know it can open your PDF — free for 3 files per day; nothing is stored.
What actually happens when you "add a password" to a PDF
Encrypting a PDF isn't a cosmetic lock screen bolted on top of the file — the page content itself gets encrypted, and a compliant PDF reader has to successfully decrypt it with the correct password before it can render a single character or image. That's why the protection holds up across every standards-compliant viewer rather than being specific to one app: the encryption is part of the PDF format itself (this tool applies it via the same library used for the site's other PDF tools), not a proprietary wrapper.
Worth being honest about the threat model this covers: it's built for everyday privacy — keeping a sensitive contract or financial document from being casually opened by the wrong person on a shared drive or in an intercepted email — not for defending a file against a well-resourced, motivated attacker with real cracking tools. As with any password scheme, a short or common password is weak protection regardless of how strong the underlying encryption is.
Frequently Asked Questions
How strong is the password protection?
It uses standard PDF encryption, which every major PDF reader respects — the file won't open at all without the password. Like any password-based protection, its real-world strength depends on choosing a password that isn't easily guessed.
What happens to my password?
It's used only in server memory to encrypt your file for this one request, then discarded immediately. It's never logged, stored, or sent anywhere else — which also means if you forget it, we can't recover it for you.
Will this stop anyone from ever opening my file?
It stops casual access — anyone without the password can't open the PDF in a standards-compliant reader. It's meant for everyday privacy (emailing sensitive documents, sharing contracts) rather than defending against a determined, resourced attacker.
Does the password actually encrypt the content, or just block a viewer's open screen?
It genuinely encrypts the page content — a compliant reader can't render any of it without first decrypting with the correct password. This is a property of the PDF format itself, which is why the protection works consistently across different PDF viewers rather than depending on one specific app's behavior.
Is my document kept on the server?
No. The file exists in server memory only for the moment it takes to process, then it's discarded. Nothing is retained or shared.