C or C++. Everything started with C and the first language for everything will be C. https://webassembly.org/docs/c-and-c++/ https://webassembly.org/docs/c-and

C or C++. Everything started with C and the first language for everything will be C. https://webassembly.org/docs/c-and-c++/ https://webassembly.org/docs/c-and-c++/ "WebAssembly is being designed to support C and C++ code well, right from the start..."