Windows 98 Disk Defrag Simulator Defrag98 is a free browser recreation of the Microsoft Windows 98 Disk Defragmenter. Pick a drive, press Start, and watch the cluster grid sort itself out to the sound of a late-90s hard disk. The simulator itself needs JavaScript, so switch it on and reload to run it. What sets Defrag98 apart from other defrag simulators

The defragmentation is simulated, not scripted. Each pass works out which clusters to read and write from the state of the disk at that moment, so no two runs lay out the same way. Nothing here is a recorded animation played back.

The cluster colors are sampled from the original Legend. Free, unoptimized, optimized, reading, writing and unmovable clusters use the exact palette of the Windows 98 Disk Defragmenter, down to the corner mark that flags an unmovable cluster.

In Fast mode it moves at most 24 clusters per pass, the same ceiling the real utility used. Every pass is charged a seek plus per-cluster transfer time, so the rhythm drifts the way a mechanical drive does instead of ticking to a fixed beat.

Realistic mode answers everyone who says a defrag was never this quick. Realistic moves at most 6 clusters per pass and triples every delay, so drive C takes about thirty eight minutes rather than eight. Windows keeps touching the disk, and each time it does the defragmenter rescans the whole drive and loses ground; dismiss the first completion box and the run never finishes again. The real one restarted the same way.

The four drives behave differently. C is 2 GB on an unhurried disk and takes the longest of the four to finish. D is 1 GB at a moderate pace. E is only 512 MB but sits on the slowest drive in the set, so its passes crawl while the whole run is over in half of C's time. F is another 2 GB volume on a quick late-90s disk and finishes fastest.

The hard-disk audio tracks the drive. Whir and clatter play at a speed set by whichever disk you picked, so a slow one grinds and a fast one skitters. The mouse clicks are the Windows 98 ones.

It runs offline. Install it once and the whole thing, sound effects included, works with no network connection.

It is free, carries no ads, and asks nobody to sign up.

Questions people askDoes Defrag98 touch the files on my computer? No. It is a nostalgia simulator and nothing more. It has no access to your disk, and it never reads, moves or modifies a single real file. The drives it shows you are invented. Is it free? Yes, completely, and there are no ads. A Buy Me a Coffee link sits at the bottom of the page if you feel like supporting it, which is entirely optional. Does it work offline? Yes. Defrag98 is an installable progressive web app. Once it has loaded, the interface, the fonts and the hard-disk audio are all cached, and it keeps running with the network off. Does it work on a phone? It does. You will get a period-appropriate warning that Windows 98 is not supported on mobile devices, which is a joke you can dismiss, and the simulator runs normally on phones and tablets after that. Why does every run look different? Because the disk is generated fresh each time and the defragmenter decides what to do as it goes. It consolidates a run of data in place when it can, drags a chunk forward from further down the disk when that is the better move, and now and then shoves a run out of the way to clear space ahead of the frontier, the same way the real defragmenter did. Which drive should I pick? C for a long, grinding session, since it takes the longest of the four. F if you want to watch it finish quickly. E for the slowest, most laborious passes, and D for something in between. Is this the Windows 95 or the Windows XP defragmenter? The Windows 98 one. Windows 95 shipped a near-identical defragmenter, down to the cluster grid and the legend behind the Show Details button, so this works as a Windows 95 defrag simulator too. Windows XP is not the same thing. Its defragmenter drew horizontal bands instead of a grid of clusters. Can I just leave it running and watch? Yes, and Realistic mode is built for it. Maximize the window and pick C, which takes the longest of the four, and it runs to the tada chime with no further clicking. In Realistic mode it then carries on indefinitely, getting close to finishing and being interrupted, which is the closest this gets to a defrag screensaver. Leave it on a desktop rather than a phone: nothing is saved between page loads. What is Realistic mode? A slower simulation you turn on in Settings. Realistic moves at most 6 clusters a pass instead of 24 and triples every delay, so drive C takes roughly thirty eight minutes. Windows interrupts it once or twice along the way: the progress line reads "Drive's contents have changed: Restarting...", the drive is read again from the top, part of it comes back fragmented, and the bar drops back. The first run still finishes. Dismiss the completion box and it never reaches a hundred percent again. Fast mode is the default and is unaffected. Who made it? Dennis Morello, a software engineer based in Milan, Italy. Defrag98 has been written up by PC Gamer, heise online, Boing Boing and kottke.org, and discussed on Hacker News and Lobsters. The simulation is documented in full in how Defrag98 works: the cluster grid, the three moves each pass can make, and the timing model behind the four drives. New features and fixes are recorded in the release notes.