Two very different kinds of PDF lock
PDFs can be protected in two separate ways, and the difference matters. An open password (also called a user password) stops anyone viewing the file without it. An owner password lets everyone view the file but restricts actions such as printing, copying text, or editing. Many documents downloaded from official sites use the second kind, which is why you can read them but cannot select text or print.
What Unlock PDF can do
Upload your file and PDF Studio first analyzes its security: whether it is encrypted, which algorithm it uses, and which restrictions are set. For files that only have restrictions, it removes them without needing any password. For files that need a password to open, enter that password and the tool decrypts the document into a normal, unrestricted PDF. Common encryption types — RC4 and AES — are supported.
Decryption runs in your browser using qpdf compiled to WebAssembly, so the document and the password stay on your device.
What it cannot do
Unlock PDF is not a password-cracking tool. If a file requires an open password and you do not know it, the tool cannot open it; it will tell you the password may be incorrect. It is meant for situations where you are entitled to the document — your own files, or files you have been given the password to — and where the protection is simply in your way.
Please respect copyright and confidentiality: removing restrictions from a document does not change who is allowed to use it or how.
After unlocking
The unlocked copy is a new file named unlocked_ followed by your original file name. Once unlocked, you can merge it, edit it, copy text from it, or convert it with the other tools. If you want to protect the result again with a new password, use Protect PDF.