PDF files are popular not only because of their universal compatibility across all the platforms but also because of their security features. PDF files can be password protected and only users with the correct passwords can access or view these protected PDF files. Furthermore, PDF files can also be secured against unauthorized modification, printing or extraction of the content. Usually we have to buy an expensive Adobe PDF software to protect the PDF files against such changes, but a freeware tool called PDF Unshare can do the same job for free.
PDF Unshare is a free PDF security software for Windows, iOS, and Android. Not only it protects the PDF files against sharing, modification, or copying, but it also introduces a new PDF format UPDF (unshared PDF). In order to view and access UPDF files, it comes with a UPDF Reader too.
For securing your PDF files, you can open them in PDF Unshare. You can choose the date on which the document is to be expired, that is, after which the document will no longer be accessible. There is an option to restrict the document to be opened only on a single device which could be a desktop computer, a notebook computer, or any of the mobile devices.
We can also add a text watermark on the PDF pages of the file being protected. We can choose the color of the text for the watermark. After entering a password, the files can be finally saved. The secured PDF file can be saved either in the UPDF format or the PDF format.
The UPDF format can only viewed using the UPDF Reader and displays all the PDF content as usual. If you save the PDF file which is compatible with other PDF viewers like Adobe Acrobat or Foxit PDF Viewer, then it will display a link to PDF Unshare which is to be installed before you can access the content.
You can download PDF Unshare from https://pdfunshare.com/.