Dave Plummer recounts the secret history of Windows ZipFolders

Dave Plummer chronicles how a bedroom side project evolved into a built-in Windows feature. He traces his roots from the Commodore 64 and Amiga work through a commercially successful Amiga product, HyperCached, which he self-published (he ordered 20 retail copies, later sold "a few thousand copies" and earned about "$15 per copy of profit") and which helped pay for college and opened a path to Microsoft (internship lead in 1992). At Microsoft he negotiated a moonlighting clause permitting outside projects with managerial approval and built ZipFolders at home as a shell extension that let Windows Explorer browse ZIP archives as folders rather than as a standalone app.

ZipFolders' implementation leveraged the shell namespace interface so Explorer supplied UI (icons, drag-and-drop) while his code handled compression and IO. Plummer identifies two concrete technical limitations he faced: 1) non-file-system folders could not provide icon arrangement metadata on Windows 95, and 2) the shell's copy engine required extracted files to exist on the filesystem, forcing a temporary staging in the temp folder and causing roughly double disk IO and slower performance.

The product's name evolved from 'Zip Explorer' (conflict with a Japanese developer) to 'VisualZip'. A shell-team complaint by the Japanese developer (referred to as Hiroshi) prompted HR action seeking his firing; escalation to a senior vice president and the general counsel produced the six-word internal legal reply: 'six words long. I have no problem with this.' Shortly after, Microsoft acquisitions contacted him to buy ZipFolders. He accepted the initial offer (later described as 'enough to purchase a quality Chevrolet motor car, but only a pre-owned one') and delivered cleaned-up code: he removed MFC dependencies by adding his own lightweight class layer, retained 32-bit/NT readiness, and shipped first in the 'Windows 95 Plus pack.' He recalls it later became part of the OS (speaker: 'I think it became part of the operating system with Windows XP in 98 or possibly in as early as NT 4') and remains present decades later (25 years).

Plummer frames the episode as a cautionary and fortunate tale about moonlighting, IP boundaries, escalation, and product-hardening for OS inclusion: ask for approvals, avoid proprietary leaks, be ready to refactor third-party-oriented code, and expect legal and acquisition dynamics when a side tool intersects your employer's business.