My physician's portal created back in 2004 is still up and running and I maintain it for the few clients left. It integrated with a larger system on the backend that wasn't mine, but has since been acquired and sunset. A few clients still run it.
My first professional programming job was back in 1996 and that software ran up through 2014, or thereabouts, until the company closed their doors. I still got the occasional call about it through the years. Good grief, that was VB3 back in those days. Yikes!