Ask HN: What nice, old software is maintained by solo dev?

This ASK HN is inspired by https://news.ycombinator.com/item?id=43716006

> yes, and this is a 30 year old software maintained by a solo dev. It's an incredible piece of internet history.

> WinRAR is also about to turn 30 in a few days.

What more such stuff do you know?