Blazor - An experimental web UI framework using C#/Razor and HTML, running in the browser via WebAssembly
Syncfusion - The world's best UI component suite for building powerful web, desktop, and mobile apps
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.
MockFlow - A super easy wireframing tool with all the other tools you need in the product design process
ASP.NET Core - With ASP.
Axure - The most powerful way to plan, prototype and hand off to developers, all without code. Download a free trial and see why professionals choose Axure RP 9.