A POSIX-style command shell compiled to WebAssembly and running in the page. Pipelines, redirection, globbing, loops, variables and command substitution all work, against an in-browser filesystem backed by IndexedDB — files you create survive a page reload.
Nothing is emulated and nothing is proxied: there is no container, no virtual machine and no server executing your commands. The shell and its builtins are Go compiled to wasm, running in the same tab you typed them into.
Source code: github.com/0magnet/websh. More Go and WebAssembly projects: magnetosphere.net/software.