Defrag98 recreates the Microsoft Windows 98 Disk Defragmenter in your browser, for free.
Pick a drive, turn on the hard disk sounds, and watch the blocks rearrange.
The cluster grid uses the colors of the original Windows 98 Legend, including the corner
mark on data that will not be moved. Every pass decides what to read and write from the
current disk layout, so each run looks different. Green shows reads, red shows writes, and
the blocks then settle into their resting colors.
There are four virtual drives, C, D, E and F, from 512 MB to 2 GB on disks of different
speeds, plus Drive G, which you size yourself in Settings.
Defrag98 is a nostalgia simulator. It runs entirely in your browser, works offline as an
installable web app, and never reads, moves or modifies any real file on your device.
The simulation is documented in
how Defrag98 works . New features
and fixes are listed in the
release notes .
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.
People also call it a fake defrag, a retro defrag screensaver, a defrag emulator, a defrag
game or just a Windows 98 simulator. They all mean this page: the Disk Defragmenter running
online, free, and oddly satisfying to leave going in the background.
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's estimate is about 61
minutes rather than 13. Windows keeps touching the disk, and each time it does the
defragmenter rescans the whole drive. A few files come back fragmented and the rest of the
finished work is kept. The run stays finished once it reaches 100 percent.
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 takes less time than C.
F is another 2 GB volume on a quick late-90s disk and finishes fastest. Drive G is yours
to set up: choose its size and speed in Settings.
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.
Frequently asked questions
Does 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. If you feel like supporting it, there is a Buy Me a
Coffee shortcut on the desktop. A coffee costs 3 euros and 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.
What do the green and red blocks mean?
Green shows data being read, then red shows where it is written. The blocks settle into
their resting colors before the next pass. Data moved out of the way flashes green only; red
marks writes into the consolidation zone. Pause freezes the current phase, and Resume
continues it.
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.
Will changing settings reset my progress?
Changing sound settings or simulation mode keeps the cluster map and progress, including a
paused phase. Selecting another drive or changing the custom drive's size or speed generates
a fresh disk.
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. Maximize the window and pick C, which takes the longest of the four, and it runs to the
tada chime with no further clicking. Windows interrupts a Realistic run once or twice before
it finishes. 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's estimate is about 61 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, a few files come back
fragmented, and the bar drops back a little. Most of the finished work is kept. The run
finishes and stays at 100 percent after you close the completion box. 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 .