I built a music player for videogame music formats because the only other player on MacOS that supported them had a terrible UI and didn't support all the formats I wanted. I consider it a tool because I use it a ton during work to play infinitely-looping songs to help me focus.

https://www.mkelly.me/moseamp/

The progression of me building the app was (over a span of maybe 7 years):

- Prototype compiling GME[1] into asm.js, generating sound samples on a webpage, and piping them into the Web Audio API.

- Turning that prototype into a desktop app in order to learn Electron.

- Giving the desktop app a proper UI in order to learn React + Redux.

- Switching to a native node.js addon to fix slowdown/memory use during playback.

- Switching to musicplayer[2] so that I could play Playstation music.

- Adding a Windows build so I could listen to music while coding on my Windows computer with the same UI as on MacOS that I had by now grown accustomed to.

- Adding a visualizer to learn how, well, visualizers work.

- Adding a piano-roll visualizer for NES music and rendering-to-video because my friends who make chiptune videos on Youtube use an old, inflexible program to make their videos.

I would say the number one driving force is that I made a tool I use pretty much every day; tools I've made that are only occasionally used never really motivate me enough to bother fixing them up, but with Moseamp every fix is an _immediate_ improvement in my day-to-day.

[1] https://bitbucket.org/mpyne/game-music-emu/wiki/Home [2] https://github.com/sasq64/musicplayer/