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WebAssembly With .NET

  • WebAssembly support for .NET is good thanks to the dotnet WASI SDK.
  • dotnet WASI SDK is an experimental package that can build .NET Core projects (including whole ASP.NET Core applications) into standalone WASI-compliant .wasm files.

Install .NET Preview (7.0.0-preview.4)

You can download .NET and follow installation instructions here:

You'll also need the Experimental WASI SDK for .NET Core available here:

.NET code

First we will have to create a new .NET console application:

dotnet new console -o MyFirstWasiApp

Replace the existing code in the Program.cs file with:

using System;

namespace MyFirstWasiApp
public class Program

public void fibonacci(ref int num){
int a=1,b=0,temp;
while(num >= 0){
Console.WriteLine("Fibonacci Term is: "+b);

public static void Main(string[] args)
Program p = new Program();
int num=10;
p.fibonacci(ref num);


Access the C# codex repository for code samples, including the fibonacci example. Please also check the following demos: Greenhouse Monitor, ICU Monitor, Confidential Trading.


Currently Experimental WASI SDK does not allow to take user input through the console using ReadLine().

Compile .NET

Import the Wasi.Sdk package so that it has support for WASI bindings.

dotnet add package Wasi.Sdk --prerelease

Build your application now using the following command:

dotnet build

The Wasm binary will be generate here: bin/Debug/net7.0/MyFirstWasiApp.wasm.

Run with Enarx

enarx run MyFirstWasiApp.wasm