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.
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Pro Fast and getting faster
Thanks to breakthroughs in ROSLYN compiler and the efforts of the .NET COre developer team, code written in C# can reach speeds just a step behind C++.
Pro Multi platform
Can run on Windows, Linux and Mac (also Visual Studio Code editor).
Pro Built-in middleware
Ability to host on IIS, Nginx, Apache, Docker, or self-host in your own process.
Both VS and VSCode are powerful free IDEs that are well integrated with ASP.net Core. VS Community also allows for commercial use for projects with less than 5 developers.
Pro Ease of Use
Pro JSON optimization
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.
It is a very secure platform.
Pro Tutorials and documentation quality
Both microsoft and 3rd party tutorials are mostly of high quality and encourage you to use the industry best-practices.