Are you familiar with using asp.net with PHP? Unfortunately, there is very little on the vbulletin5 API at this point and I am far from an expert on the subject. Most of us at this point just snoop around in the vBulletin5 code to gain our insight. I certainly have used asp.net and .net languages with PHP, but have not used them in conjunction with the vBulletin5 API. Using asp.net with vbulletin, should follow the outline of executing any PHP with asp.net. Sorry, I found your questions a bit to broad in scope to provide you with a helpful answer. If you have a more specific question about the API, we might be able to help.