Independent .NET for WebAssembly and WASI.
Write C#. Deploy small, standalone Wasm.

NetWasm is an independent compiler, CoreLib, runtime and SDK that compiles C# and .NET CIL directly to WebAssembly. It does not carry the desktop CLR, Mono, dotnet.js or application DLLs into production.

Compile C# to WebAssembly · Try it in the browser · Install and build · See supported APIs · Read the documentation

NetWasm + precise GC: 47,895 bytes
Rust 1.95.0 size-oriented profile: 53,635 bytes

For the same print-42 workload, NetWasm's result includes the runtime and precise Compact garbage collector. Both artifacts are standalone WASI Preview 2 Components, built the way a developer gets them out of the box: each toolchain's standard library and ordinary build, with no hand-added tools.

10.7% smaller raw. 19.5% smaller with Brotli-11.

Rust is the headline comparison because it uses the same workload and output form. Kotlin/Wasm and TinyGo show the broader footprint landscape, but their targets and runtime boundaries differ. This is a measured workload/profile result, not a language-wide size ranking.

NetWasm's figure is the template application's default Release publish. Rust's adds Cargo's documented size settings (opt-level = "z", LTO, one codegen unit, panic = "abort" and stripped symbols) to an ordinary cargo build. Binaryen's wasm-opt is not a post-processing step here: it is part of NetWasm's compiler pipeline and runs in every ordinary build, with nothing to install or enable. Rust's wasm32-wasip2 output is a component, so applying wasm-opt to it means extracting the core module, optimizing it and re-encoding the component by hand.