CheerpX is a state-of-the-art Virtual Machine that runs purely client side in your browser.

Main project link: https://leaningtech.com/cheerpx/

Demo: client side REPL

Execute, directly in your browser, the Read-Eval-Print Loop for the unmodified x86 binaries of Python, Ruby or Node.js. Try this live at: https://repl.leaningtech.com/.

Explainer

Yuri Iozzelli talks about CheerpX internals at WasmSF: