Password Protect PDF

Is my password or my file sent anywhere?

No. The file is encrypted in your browser tab, and the password never leaves it — HerePDF does not upload, log or save it, not even in your browser’s storage. Close or reload the page and it is gone. Your browser’s password manager may offer to save it for you; that is its choice and yours, and it is a good place to keep one.

How strong is the encryption?

AES-256, the strongest encryption the PDF format supports and the only kind its current standard recommends. It is also considered safe against future quantum computers, which at most halve its effective strength. In practice the weak point is the password: anyone with the file can try guesses as fast as their computer allows, so a long password — a few random words — matters far more than anything else.

What does the password actually hide?

The pages’ text and images, their layout, and the document’s properties (title, author and so on) are all encrypted. What stays visible to someone without the password is the file’s size and its rough shape — how many separate blocks of data it holds and how big each is — which can hint at whether it is a long document or a short one.

Which apps can open the protected file?

Any current PDF reader: Adobe Acrobat and Reader, Apple Preview, and the viewers built into Chrome, Edge and Firefox all ask for the password and open it. Readers from before about 2010 do not support AES-256 and cannot open it at all.

What if I forget the password?

Then the file cannot be opened — by you, by HerePDF, or by anyone else. There is no recovery, reset or back door, which is the point. Keep the password in a password manager, and keep an unprotected copy of the original somewhere safe if you might need it later.

Can I stop people printing or copying instead?

Not here, deliberately. PDF “permissions” are only honoured by readers that choose to honour them, and many tools ignore them, so offering them would suggest a protection that isn’t real. With this tool, anyone who has the password can do anything with the document; anyone who doesn’t cannot read it at all.

Why are some characters not allowed in the password?

Some characters — full-width letters and digits from Chinese or Japanese keyboards, ligatures like “fi”, accents typed separately from their letter, or the non-breaking spaces that often come with text pasted from a document — are converted by some PDF readers before checking the password and not by others. A password containing them could open in Acrobat but not in Chrome, so HerePDF asks for ordinary letters, numbers, symbols and spaces instead.