Here it is a simple software for splitting pages in half without using online tools or heavy software with lots of other stuff.

From this post on Stackoverflow, I added the support for the drag and drop of files in Windows; all you have to do is drag the PDFs over the executable file Auto-Cut.exe.

Note: sometimes, if the PDF is flawed, the tool will make the wrong cut; in that case use the tool called Vertical-Cut.exe or Horizontal-Cut.exe.