I've been developing Rails apps since 2006, and I even built a simple Rails clone called Dubious in Mirah. This was useful for scaling Rails apps on Google App Engine for Java.

I created Caltrain apps with J2ME and later for KaiOS. The KaiOS version is a PWA written with VanillaJS.

This project has obviously evolved into a smartphone app in Swift and Kotlin.

Additionally, I like to implement algorithms in several languages to refresh my memory on syntax and features. I've also created some obscure Docker images like nanoserver-ruby and geminabox.