HTML5 - 5th major revision of the core language of the World Wide Web
Blazor - An experimental web UI framework using C#/Razor and HTML, running in the browser via WebAssembly
Angular.io - Angular is a JavaScript web framework for creating single-page web applications. The code is free to use and available as open source. It is further maintained and heavily used by Google and by lots of other developers around the world.
ASP.NET Core - With ASP.
Kendo UI - Fast, light, complete: 70+ jQuery-based UI widgets in one powerful toolset
B4X - Cross platform development tools for native iOS, Android, desktop and server applications.