Defrag98 is an online disk defragmenter simulator that recreates the experience of Windows 98's built-in defragmentation tool. The website allows users to upload files and watch them reorganize themselves using the same algorithm that powered Windows 98's defrag utility. Created as a nostalgic throwback, the simulator captures the exact visual style, timing, and behavior of the original tool that many users remember from the late 1990s.

The project has gained traction on Hacker News, where it currently sits at 89 points with 45 comments, sparking discussions about retro computing and software preservation. The site cleverly mimics the dated interface, including the characteristic green progress bar and the methodical reorganization of virtual disk sectors. For those who lived through the Windows 98 era, Defrag98 offers a surprisingly authentic recreation of a task many performed regularly but rarely thought about.

The simulator works entirely in the browser, requiring no software installation while delivering a genuine piece of computing history.