I know I don't want an [add-in](https://dev.office.com/docs/add-ins/overview/office-add-ins) to any existing Office 365 application.

I want to be able to develop a .net application that will be able to query multiple data sources and live inside of Office 365 to display data the way I code it to.

The data I will be querying lives in places like Active Directory, Dynamics AX, Sharepoint, etc.

Is this a thing that Office 365 is capable of doing? I'm unable to find examples of this (which makes me think no) but I am also unable to find a source explicitly saying you can't do this. This is not limited to HTML/JS, I want to be able to write back-end functionality.

Please help.