KolibriOS

2004 → today · Independent

A tiny, free operating system that grew out of MenuetOS in 2004.^{1, 2} Its kernel and most drivers are in assembly language, which keeps it fast.^{1, 4}

▶ Try it Sources

First release: 16 May 2004³
Grew out of: MenuetOS¹
License: GNU GPL version 2²
Our lesson uses: A nightly build on a floppy disk image²

How it began

KolibriOS split off from MenuetOS in 2004 and has been developed on its own since then.¹ MenuetOS was written by Ville Turjanmaa, and KolibriOS still keeps its copyright notices. As of November 2026, a small team of enthusiasts builds KolibriOS as a hobby system.⁴

KolibriOS desktop at 1024 by 768: a dark starry background with a gray drawing of a round house on a small planet, rows of program icons in the corners (such as KFM2, CALC+, TINYPAD, NETSURF, SHELL, TETRIS, SNAKE and MINE), and a taskbar with a green Menu button at the bottom left. — The KolibriOS desktop, a few seconds after our virtual PC starts from the floppy disk image. We measured that image at 1,474,560 bytes, the size of one 1.44 MB floppy disk.

What it looks like

KolibriOS starts up to a graphical desktop, and its programs open from icons. Its kernel and most drivers are written entirely in FASM assembly language, which makes them fast.^{1, 4} Assembly language also keeps them very compact.⁴ KolibriOS follows its own standards and is not fully Unix-compatible.⁴ It comes with a text editor, image viewer, paint program, web browser and more than 30 games.¹

KolibriOS desktop with the Calc+ calculator window open in the middle. Its display shows the calculation 12 × 34 = 408 (typed as 12*34), above a keypad with digits and operator buttons. — The CALC+ calculator, which our lesson opens with a double-click on its desktop icon, showing 12 × 34 = 408.

Where it is today

As of November 2026, the newest numbered release is still Kolibri 0.7.7.0, from December 2009.³ Instead, the team shares nightly builds with the latest changes. A floppy disk image is still one of them, for emulators and real floppy drives.²

KolibriOS desktop with a 'Tetris 1.62' window open: a black playing field with a few colored blocks stacked in the middle, a score of 4, and New Game and Pause buttons below. — Tetris, one of the games on the floppy disk image, running in our virtual PC.

Key moments

2004 The first release, Kolibri 0.1.0.0, comes out on 16 May.³
2006 Version 0.6.0.0 comes out on 4 September. Releases from then until 2007 include a loader that can start KolibriOS straight from Windows.³
2009 Kolibri 0.7.7.0 comes out on 13 December.³
2026 KolibriOS is accepted into Google Summer of Code 2026.¹