Blazor is a client side framework utilizing web assemblies.

Components for this framework must be built as blazor web assembly components.

The assemblies you build end up in your bin folder with extension dll - but you will also need to have include the component in Blazor application, because when Visual Studio builds the application it creates further variant files of your assembly that we will need.

The App is pretty much an empty shell taken straight from the wizard in Visual Studio for the BlazorApp - we add a project reference to the RazorClassLibrary1 project - this is the project that will produce the assembly with our Component1.