WebAssembly is actually simple to work with.

If you want to obtain a "C" pseudocode, you can give a wasm file to wasm2c [1].

You can re-obtain a WebAssembly folded-expression text format using wasm2wat [1].

You can obtain a call-graph from a WebAssembly module by generating the wat representation using wasm2wat and pasting it into main.wat on https://webassembly.studio/ (-> Empty Wat Project). Then save and build; right click the new main.wasm and select "Generate Call Graph."

That said, check out this encrypted and anonymous "pastebin" I built [2] with the crypto being written in Rust and bindings generated using wasm-bindgen [3]. It surprisingly hard to debug when optimized using wasm-opt [4].

[1] Part of WebAssembly Binary Toolkit: https://github.com/WebAssembly/wabt

[2] Source code on Github: https://github.com/psychonautwiki/impis/blob/master/core/src... — Demo paste: https://imp.is/n/7NFsfEiCjkFBVgC6A4JS6GyqN7puN5Sg7ed11m8VrtT...

[3] https://github.com/rustwasm/wasm-bindgen

[4] Part of Binaryen: https://github.com/WebAssembly/binaryen