Lock/Unlock PDF
Add a password a PDF needs to be opened, restrict what a reader without it can do, or remove a password you already know. Nothing is uploaded — it all happens in your browser.
More about this tool
Locking writes a real password into the PDF’s own encryption — the same AES-256 every current PDF reader already supports, not a note asking someone nicely not to open it. A password to open the file is one thing; a separate permissions password is another, restricting printing, copying or editing even for a reader who was never asked for a password at all. Unlocking runs the other way: given the password a protected file already has, it writes out the same document without it.
When to use it
Locking, before sending a document that should only reach the person it is addressed to, or one that should be readable but not edited or printed further. Unlocking, once a file you have the password to no longer needs protecting — after that, printing, copying and editing all work again at no cost to fidelity.
What it will not do
This only removes a password you already know. It does not recover a forgotten one, and it does not attempt to bypass or crack protection on a file that is not yours to open — if that describes the file, this is not the right tool, and no tool run in a browser tab honestly is one.