There are use-cases where you want to start multiple projects of your solution at once in Visual Studio. For example if you’re developing a website in Asp.Net Core MVC getting it’s data of an Asp.Net Core Web API application. You’ll have to do the following steps to set multiple startup projects:
1) Right click on the top node of your solution in the solution explorer.
2) In the context menu choose Properties (Alt + Enter).
3) Expand the „Common Properties“ node, and choose Startup Project.
4) Select the Multiple Startup Projects radio button option and set the appropriate actions.
The way with less clicks is to click on the little arrow on the left side of the start button and choose Define Start Projects or right click on the solution node and choose Define Start Projects.