With ASP.NET Core you can build web apps, web services, IoT apps, and mobile backends. It can be used with Visual Studio, or with Visual Studio Code, see article on Medium Getting started with ASP .NET Core.
.NET Core 3 Preview is announced. ASP.NET Core 3 enables client-side development with Razor Components.
In .NET Core 2.1 and 3.0, new APIs are added that make it possible to write JSON APIs that require less memory, using Span<T> and UTF8 strings, and improve throughput of applications like Kestrel, ASP.NET Core web server. See also Utf8JsonReader.
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Pro Fast and getting faster
Pro Built-in middleware
Ability to host on IIS, Nginx, Apache, Docker, or self-host in your own process.
Pro Multi Platform
Can run on Windows, Linux and Mac (also Visual Studio Code editor).