NetWasm

Compile C# and .NET CIL to small standalone Wasm with WASI (AOT with built-in Runtime and Precise GC)

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4Distinct people

4Mentions

0Explicit recommenders

334GitHub stars

REPOSITORY AT A GLANCE

What to know before exploring

What it is

Compile C# and .NET CIL to small standalone Wasm with WASI (AOT with built-in Runtime and Precise GC)

GitHub

Where it is used

No documented product use has been verified yet.

What people are saying

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Also in these discussions

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This week on Hacker News

Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 5:04:57 PM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by day4 dated mentions

Observed mentions: 2026-09-29 13:09:27 UTC to 2026-10-21 10:24:37 UTC.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges

UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
Period	Start (UTC)	End (exclusive, UTC)	Mentions	Submissions	Comments
Sep 29	2026-09-29 00:00:00 UTC	2026-09-30 00:00:00 UTC	1	1	0
Sep 30	2026-09-30 00:00:00 UTC	2026-10-01 00:00:00 UTC	0	0	0
Oct 1	2026-10-01 00:00:00 UTC	2026-10-02 00:00:00 UTC	0	0	0
Oct 2	2026-10-02 00:00:00 UTC	2026-10-03 00:00:00 UTC	0	0	0
Oct 3	2026-10-03 00:00:00 UTC	2026-10-04 00:00:00 UTC	0	0	0
Oct 4	2026-10-04 00:00:00 UTC	2026-10-05 00:00:00 UTC	0	0	0
Oct 5	2026-10-05 00:00:00 UTC	2026-10-06 00:00:00 UTC	0	0	0
Oct 6	2026-10-06 00:00:00 UTC	2026-10-07 00:00:00 UTC	0	0	0
Oct 7	2026-10-07 00:00:00 UTC	2026-10-08 00:00:00 UTC	0	0	0
Oct 8	2026-10-08 00:00:00 UTC	2026-10-09 00:00:00 UTC	0	0	0
Oct 9	2026-10-09 00:00:00 UTC	2026-10-10 00:00:00 UTC	0	0	0
Oct 10	2026-10-10 00:00:00 UTC	2026-10-11 00:00:00 UTC	0	0	0
Oct 11	2026-10-11 00:00:00 UTC	2026-10-12 00:00:00 UTC	0	0	0
Oct 12	2026-10-12 00:00:00 UTC	2026-10-13 00:00:00 UTC	0	0	0
Oct 13	2026-10-13 00:00:00 UTC	2026-10-14 00:00:00 UTC	0	0	0
Oct 14	2026-10-14 00:00:00 UTC	2026-10-15 00:00:00 UTC	0	0	0
Oct 15	2026-10-15 00:00:00 UTC	2026-10-16 00:00:00 UTC	0	0	0
Oct 16	2026-10-16 00:00:00 UTC	2026-10-17 00:00:00 UTC	0	0	0
Oct 17	2026-10-17 00:00:00 UTC	2026-10-18 00:00:00 UTC	1	1	0
Oct 18	2026-10-18 00:00:00 UTC	2026-10-19 00:00:00 UTC	0	0	0
Oct 19	2026-10-19 00:00:00 UTC	2026-10-20 00:00:00 UTC	0	0	0
Oct 20	2026-10-20 00:00:00 UTC	2026-10-21 00:00:00 UTC	0	0	0
Oct 21	2026-10-21 00:00:00 UTC	2026-10-22 00:00:00 UTC	2	1	1

What Hacker News says

4 sources

drhagen·Oct 21, 2026

TFA did [0] the most important stuff for minimizing Rust binaries: release mode, LTO, strip, and abort on panic. But there is a lot more you can do if you really care about Rust binary size [1]: remove location details, purge the debug formatters, rebuild the standard library for size, abort with no error message at all, and nuttier stuff. [0]: https://github.com/zion-sati/NetWasm/blob/main/docs/size-and... [1]: https://github.com/johnthagen/min-sized-rust

In C# now beats Rust on WASM size

sumnole·Oct 21, 2026Submission

C# now beats Rust on WASM size

161 points · Open discussion

theanonymousone·Oct 17, 2026Submission

C# now beats Rust on WASM size

8 points · Open discussion

zionsati·Sep 29, 2026Submission

Show HN: NetWasm – Independent .NET Compiler/Runtime (82.5 KB Hello World in C#)

I’ve been building NetWasm: an independent .NET compiler, CoreLib and runtime designed specifically for WebAssembly. It compiles Roslyn-generated CIL into standalone core WASM or WASI Preview 2 components - without shipping CoreCLR or Mono. A clean Release application containing Console.WriteLine(42) produces 82.5 KB of final WASM with WASI p2, including the runtime and precise garbage collector. Website: https://www.netwasm.com/ Playground: https://playground.netwasm.com/ The playground runs fully on the browser without a backend / cloud server compiling your code - it's all WASM! Locally, you use dotnet new, dotnet build, dotnet test, etc like you would normally. You can run the self-contained .wasm output with wasmtime, fully portable. GitHub repos: https://github.com/zion-sati/NetWasm https://github.com/zion-sati/NetWasm.Libraries Wha

Read the rest

t is it? It's CIL (used to be called MSIL - it's the dotnet bytecode in other words) to WASM compiler. But more than that it's intentionally not using Microsoft's Corelib. We avoid reflection, typename with full namespace strings etc where the resulting .wasm can end up bloated. The goal is to have C# (and later .NET in general - thus F# and VB.NET) be on equal footing as Kotlin/WASM. Note that Kotlin/WASM uses WasmGC, NetWasm uses BoehmGC in precise mode. NetWasm makes Wasm a first class target. Why NetWasm? I fell in love with C# in 2006 and have OSS attempts at building C#-like syntax using C++ template metaprogramming with BoehmGC a long time ago because I didn't like the idea of having a runtime pre-installed. This idea was revitalized when I tried to migrate my web UI framework FUI-RS to C# - the resulting smoke test was already a minimum of 1 MB Brotli compressed running in interpreter mode! FUI-RS (Rust) had it at under 50 KB uncompressed. What already works? C# 15, precise GC, finalization, exceptions, generics, virtual/interface dispatch, LINQ, tasks / value tasks (thus async-await), JSON, dependency injection, regex, XML, HTTP, WIT/WASI and TUnit (a modern source generated unit testing framework) etc. What's left to do? There's a roadmap to v1.0 on the repo's README - tl;dr there's a lot to do before we can get there, e.g. Expression trees, faster dev loops, threading, web workers, interop via libimport and globalization (opt-in just like NetWasm's implementation of timezone info). NuGet packages should be able to multitarget to support NetWasm as well as the full .NET as long as there's no reflection / typename involved. Licence: Runtime, CoreLib, templates and libraries: MIT Compiler and tooling: NetWasm Community License Note that NetWasm is pre-1.0 (currently v0.5) and evolving rapidly, so I'd appreciate any technical feedbacks from the community if you'd like to help me shape this project. Particularly, real WASI use cases people want supported, NuGet packages to multitarget (or even better if you're one of the popular open source packages and would like to start multitargeting).

6 points · Open discussion