WASI is just a set of standardized interfaces that any WASM host can implement. So while there’s no WASI out of the box on browsers, there’s nothing preventing

WASI is just a set of standardized interfaces that any WASM host can implement. So while there’s no WASI out of the box on browsers, there’s nothing preventing you as a developer from bringing your own implementation (in which, for example, writes to stdout could sent to console.log, and files could be backed by an in memory VFS). See this article, where the mention (and link to) polyfill on browsers: https://hacks.mozilla.org/2019/03/standardizing-wasi-a-webassembly-system-interface/ https://hacks.mozilla.org/2019/03/standardizing-wasi-a-webas...