Defrag98 recreates the Windows 98 Disk Defragmenter in your browser, down to the window chrome and the bitmap fonts. Pick one of four drives, press Start, and watch the cluster grid sort itself out to the sound of a grinding hard disk. It touches no real files. Everything it defragments is imaginary.

What it does

Each drive has its own capacity and speed, so C fills slowly and the smaller drives tear through. The cluster map shows reads in green and writes in red as blocks get pulled from the tail of the disk and packed into the front. There's a Legend dialog, a progress bar that reveals itself in chunky segments, and an estimated time remaining that is as trustworthy as the original.

Sound is on by default: hard drive noise while it works, and a click on every button. Both can be turned off in Settings if you have colleagues.

It installs as a PWA and runs fully offline. There's also an Easter egg. If you grew up on Win98 you'll know it when you see it.

How it's built

React 19 and TypeScript on Vite, with Tailwind CSS and Zustand. The cluster map is drawn to a canvas rather than the thousands of DOM nodes the first version used, and it's viewport virtualised so large drives stay smooth on mobile. No cookies, no consent banner.

Background

I built the first version in 2024 as a weekend project. It ended up on Hacker News and in The Verge, which was not the plan. Two years later I rewrote it from scratch, because the original simulation was too orderly: it marched left to right like a progress bar with extra steps, where the real thing moved solid blocks around in a way that looked like a machine thinking.