Emscripten

An LLVM-based compiler toolchain that compiles C and C++ code into WebAssembly for high-performance execution in web browsers.

Emscripten bridges the gap between systems programming and the web by compiling LLVM bitcode into WebAssembly (Wasm). It handles complex ports for industry standards like the Unreal Engine, Unity, and AutoCAD: providing the necessary headers and libraries to run desktop-grade software at near-native speeds. Developers use it to migrate existing libraries (such as SQLite or FFmpeg) into browser environments without rewriting core logic. By mapping OpenGL to WebGL and supporting the WebAssembly System Interface (WASI), Emscripten delivers a complete execution environment for the modern web stack.

https://emscripten.org