edenix
A whole operating system that boots in your browser tab — a POSIX-ish shell over a docker-style copy-on-write filesystem, coreutils you can pipe, programs you can write, and a windowed desktop, all client-side.
This is an operating system that runs entirely inside this page. There is no server, no virtual machine, no Linux hiding underneath — just TypeScript pretending to be a kernel, convincingly enough that a real shell, real coreutils, and real programs believe it.
The filesystem is docker's: one immutable base image plus a copy-on-write layer per container, whiteouts and all.
The shell tokenizes and parses like sh does, with pipes, redirections, globs, and command substitution.
The coreutils are the ones your fingers already know — ls, grep, find, xargs — talking to the kernel through nothing but syscalls.
You can write your own #!/bin/sh and #!/usr/bin/js programs in the editor and run them like any other binary.
Boot it, open a terminal, and poke around.
Everything you change persists across reloads; machine reset wipes it back to the pristine base.