Hi Bruno,
Thanks for considering The Events Calendar as a possible solution for your site update. Our product is a WordPress plugin, and WordPress runs on PHP, so no native support for .NET. However WP.NET is a project that enables WordPress to run smoothly in a .NET environment.
Regarding the import, our product comes with a CSV Importer that lets you import venues, organizers and events directly from csv files into your WordPress site. You can find further information about the CSV Importer in this Knowledge base article.
Do you think this might work for you?
Best,
Nico