What this does, and what it will not do
This tool decrypts a PDF using the password you give it, then saves the result without any security handler. It is the same operation your PDF reader performs when it opens the file — the difference is that the decrypted version is written back out.
It does not attempt to recover an unknown password. There is no dictionary attack, no brute force and no bypass. If the password is lost, the document is genuinely closed, and any site claiming otherwise is either lying or was working on a file that was never really encrypted.
Password versus permissions
PDFs carry two separate things. An open password encrypts the contents — nothing can be read without it. A set of permission flags asks readers not to allow printing, copying or editing, and is honoured by convention rather than enforced.
If your file opens straight away but refuses to print, it has the second and not the first. This tool checks which you have and says so rather than asking for a password the document does not use.
Why removing it is often the sensible thing
Encrypted PDFs interact badly with a lot of software. Editors refuse them, print services reject them, e-signature platforms cannot ingest them, and phone readers handle them inconsistently. When a document is going to be worked on repeatedly, keeping one decrypted copy somewhere safe is usually less risky than emailing the password around every time someone needs it.
Both halves stay on your device
The whole point of the exercise is confidentiality, so uploading the file and its password to a stranger's server would be a strange way to go about it. Everything here happens in your browser tab. You could disconnect from the network after the page loads and it would still work.