PDF files can have restrictions that prevent you from for example copying text from them or editing, printing ormerging them. PDFUnlock! can remove these restrictions (a.k.a "owner password").
If a password is required to open the uploaded file, you will be asked to enter it (a.k.a "user password"). PDFUnlock! cannot, however, recover lost or unknown user passwords.
A PDF file can also be subject to non-standard encryption, such as DRM. PDFUnlock! does not remove such.
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