copy.sh is a website which lets you emulate a VM online in your browser.
You can run:
|Arch Linux 12 MB||A complete Arch Linux restored from a snapshot, additional files are loaded as needed|
|D Small Linux 50 MB||Graphical Linux with 2.4 kernel, Firefox 2.0 and more. Takes 1 minute to boot.|
|Buildroot Linux 5.0 MB||Minimal Linux with busybox, Lua, tests, internet access, ping, telnet and curl. Exchange files through |
|ReactOS 18 MB||Windows-compatible OS. Restored from snapshot|
|Windows 2000 24 MB||Including Pinball and Internet Explorer with internet access. Additional sectors are loaded as needed.|
|Windows 98 9.7 MB||Including Minesweeper and Internet Explorer with internet access. Additional sectors are loaded as needed.|
|Windows 95 4.6 MB||Restored from snapshot|
|Windows 3.1 15 MB||Takes 15 seconds to boot|
|Windows 1.01 0.6 MB||Takes 1 second to boot|
|MS-DOS 6.22 4.4 MB||With Enhanced Tools, QBasic, vim, games and demos.|
|FreeDOS 0.5 MB||With nasm, vim, debug.com, Rogue, some games and demos.|
|FreeBSD 17 MB||FreeBSD 12.0 base install. Restored from snapshot.|
|OpenBSD 12 MB||OpenBSD 6.6 base install. Restored from snapshot.|
|9front 4.4 MB||A Plan 9 fork.|
|Haiku 46 MB||Restored from snapshot. Includes network support.|
|Oberon 1.2 MB||Native Oberon 2.3.6|
|KolibriOS 1.4 MB||Fast graphical OS written in Assembly|
|QNX 1.3 MB||QNX 4.05 Demo disk (no networking)|
|Snowdrop 0.3 MB||A homebrew operating system from scratch, written in assembly language|
|Solar OS 0.3 MB||Simple graphical OS|
|Bootchess 512 B||A tiny chess program written in the boot sector|
|SectorLISP 512 B||A LISP interpreter that fits into the boot sector|
It saves the OS for later use in your web browser cookies! You can restore the os with no problem whenever you want because the os is stored inside a cookie.
There is a lot of OSes to choose from, including some old ones.
On the custom VM side, you can select an image and boot directly from your web browser.