Try the live demo

Otium is a little operating system project that I worked on from September to December of 2025.

It's a simple microkernel that runs on RISC-V (under QEMU) or on WebAssembly.

Features:

• The shell is a small implementation of Tcl so normal programming works
• Graphics, filesystems and input devices support are just processes, which can crash normally without impacting the overall system
• A cooperative scheduler, which is implemented using Emscripten fibers on WebAssembly

For more information including instructions on how to build and use the operating system, see the website at otium.sh.

Screenshots

Tcl shell with taskbar showing running processes:

Graphics demo with concentric circles:

Links

• otium.sh - website
• devlog - dev log