v86 emulates a Pentium 4 class x86 CPU and translates machine code to WebAssembly, allowing for browser-based emulation. It also emulates various hardware so you can run full operating systems right inside your browser!

There are example images hosted by the author for everything from various DOSes up to Windows 2000, QNX, OpenBSD, ReactOS, AROS, Arch HURD, Minix, and a tonne of others!

Live examples: https://copy.sh/v86/ Github: https://github.com/copy/v86