Different programming languages in ASP.NET

The use of multiple programming languages within an ASP.NET web application is referred to as interoperability, commonly known as "interop." ASP.NET provides the flexibility to utilize different programming languages for different pages within the application. However, it is important to note that each page must be written entirely in a single language. This means that each .aspx file corresponds to a specific programming language, such as C# or Visual Basic .NET. While it is possible to mix languages within a single application, it is not allowed within a single page.


An ASP.NET page is restricted to code written in a single programming language. The default language is Visual Basic , but any other language can be declared as the default language for the page by placing a directive at the top of the page, such as the following:

< %@Page Language="C#"% >

While it is true that only one language can be used on a single page in ASP.NET, it is possible to incorporate user controls written in different languages, including Visual C++. This flexibility allows applications to utilize the functionality provided by various function libraries written in different languages.


The ability to use multiple languages within the same ASP.NET project proves beneficial in several scenarios, particularly when integrating existing code from different sources and when working with developers who possess diverse skill sets. It is important to note that all code within the App_Code folder must be written in a single language. However, you can create subfolders within the App_Code folder and assign a different language to each subfolder, enabling the coexistence of multiple languages within the project. folder.