I you did the naive add two number example, you probably also included the whole standard library.

If you really want to go down in size, you either need to compile without the standard library and/or use wasm-gc and wasmopt to remove all the useless code that have been added to your wasm binary.

With this, you can generate wasm binary that weight only a few hundreds octets.

There's a lot of stuff going on. Depending on which rust you used, we didn't do a lot of dead code elimination by default, and the default settings don't optimize for size. The 100 byte thing is the "add two numbers" function, but you have to do a few things.

See here: https://rustwasm.github.io/book/game-of-life/code-size.html

In the future, it will do more of the right things by default, but for now, you have to do some configuration if you want the tiniest possible binary. Early days!

the tooling is quite immature at the moment - and tools like Emscripten especially add a lot of bloat. In the future wasm modules will be a lot slimmer. The Rust community are certainly leading the way on that one.

Which target are you using?