These are some projects I did for web & mobile development earlier on in my career.
A messaging app on Firebase
A messaging app written in Kotlin using Jetpack Compose and Firebase. Up until this point, I used to do test-driven development for every piece of software I wrote. It turns out that a proper system architecture, static testing, and a good declarative library are more efficient than using TDD for UI development.
A REST API for a mock Bitcoin wallet
A REST API for a mock Bitcoin wallet, built with FastAPI. There's nothing special about this project, other than that it was a good demonstration of how effective a good extreme programming approach is. I wrote the whole thing in a few hours and everything worked on the first try (and there were no coding agents back then).