Browser-based .NET IDE with visual designer, NuGet packages, code share

What it does

Design, build & run .NET apps in your browser with C# and XAML. Visual drag-and-drop designer, WebAssembly compilation. Free, no signup, no install.

In the maker’s words, at launch

Hi HN, I'm Giovanni, founder of Userware. We built XAML.io, a free browser-based IDE for C# and XAML that compiles and runs .NET projects entirely client-side via WebAssembly. No server-side build step. The link above opens a sample project using Newtonsoft.Json. Click Run to compile and execute it in your browser.…

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  Firefox in WebAssemblyJul 2026 · developer.puter.com · ▲273

  This is the entire Firefox browser rendering to a element. Gecko, all UI components, and the Spidermonkey JS engine are all compiled and running in WebAssembly. Here are a few things you might find interesting: - This is fully end to end encrypted! We use the WISP protocol for TCP-over-websockets. - There is a novel WASM->JS JIT for experimental site speedup - This port cost over 25k in opus/fable tokens for debugging and JIT research This was just a fun experiment to push the boundaries of WebAssembly. For a more usable "browser in browser" experience, we also built…

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  Insomnia Designer – Open-source collaborative editor for API design2020 · insomnia.rest · ▲317

  Leading Open Source API Development Platform for HTTP, REST, GraphQL, gRPC, SOAP, and WebSockets

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  DotNetFiddle – JsFiddle for .Net2013 · dotnetfiddle.net · ▲217

  Test your C# code online with .NET Fiddle code editor.

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  Dropbase – Build internal web apps with just Python2023 · github.com · ▲207

  Hey HN, I’m Jimmy, co-founder of Dropbase (https://www.dropbase.io). We are an internal tools builder for Python developers. All you have to do is import any Python scripts/libraries, declare UI components, and layer app permissions so you can share them with others. We’re a middle ground between Airplane and Retool—simpler UI creation than Airplane, more code-centered than Retool. UI building is declarative and you can bind Python scripts/functions to UI components. You can write Python scripts/functions using our App Studio with support from a Python Language…

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  How to compile C/C++ for WASM, pure Clang, no libs, no framework2022 · github.com · ▲217

  A little help for programmers, who wants to run C/C++ code in the browser. (This is my second attempt to show it, first time I got banned bcoz of my personal page domain, I don't really understand it why is is suspicious.)

• IW
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