ToaruOS (also known as ToAruOS or とあるOS; 'toaru' is Japanese roughly equivalent to 'a certain') is a hobby operating system[1] and kernel developed largely independently (notably contrary to most modern OSes, which are based on existing source code) by K. Lange.

[6] It has support for GCC, Python, and Simple DirectMedia Layer as well as many open-source utilities – including Vim.

[3] The userspace also has a window manager, Yutani (named after the Weyland-Yutani Corporation from the Alien franchise, and as a reference to the Wayland Display Server for Linux), with input support.

[6] It stores windows as shared memory regions with 32-bit colour, and uses pipes to communicate to other parts of the OS.

[7] For April Fools' Day 2015, Lange released PonyOS, a version of ToaruOS themed after the animated series My Little Pony: Friendship Is Magic.