If you've ever agonized creating an add-in for another product, you are in for a real treat. 

In Qasper, an add-in is a quick, 4-step process. No API, no complex interface code. 

Just write your web-based .NET application and link it in through Qasper's XML-based menu system:

1. Develop your project in .NET. 

2. Deploy the compiled DLL and any required supporting .NET DLLs to the Qasper Office web folder's /bin folder.

3. Deploy the various forms for the add in application in a sub folder of Qasper Office's web folder.

4. Add a menu item to any one of Qasper's menus. See Custom Menus - Adding in a custom application: .NET add-ins for add in information. 

Simple, quick, complete. Because it's .NET, your app will have access to the session variables, including configuration variables like the database connection string, so you can work with Qasper's database.

Your app will also have access to the active user variables, so you'll be able to perform authentication.

Think of the possibilities ... (By the way, Qasper Widgets is an add-in)

If you aren't working with .NET, you can still use Qasper's XML-based menu system to link to any of your web-based applications. Of course, you won't have access to the session variables, but you can write your code to handle that.