Helium is a free, open-source student planner: web app, native iOS and Android apps, and an open API. I started building it in 2009 as a frustrated CS student, when nothing available felt both simple and capable.
The original was a cross-platform desktop app called Get Organized. The first conceit was a calendar that doubled as a todo list — every assignment a checkbox you could tick off, just for the satisfaction. Fifteen years and many rewrites later, it's Helium.
Stack: Django + DRF on the backend, Flutter on the frontend. MIT-licensed on GitHub. No ads, no VC,
supported by Patreon. Still just me writing the code, with feedback from the people who use it every day.
It's used by students from middle school through grad school. Happy to answer questions about the stack, the architecture, design decisions, or what it's like maintaining a side project for this long.