LGKA+
LGKA+ is the daily driver for Lessing-Gymnasium Karlsruhe: substitution plans, timetables, school news and events, absence reporting, and live weather from the school's own station. Most of the school checks it before deciding whether to get out of bed.
The users
Over 500 of roughly 600 students use it daily — on school-managed devices and personal phones alike. That number is the hard part. Anyone can build a substitution-plan app; getting a whole school to adopt one, keep it installed, and open it every morning for over a year is the actual engineering problem. The feedback loop is brutal and wonderful: if something breaks, I hear about it in the hallway within minutes.
What it does
- Substitution plans, parsed from the school's PDFs into something readable on a phone
- Personal timetables
- School news and events
- Absence reporting, so sick notes don't require a phone call at 7 a.m.
- Live weather from the school's weather station
The numbers
Fourteen months of development, 1,085 commits, one codebase for iOS and Android. It shipped in June 2025 and has been in continuous daily use ever since. These days it's stable software in maintenance mode — it does its job, and it gets touched when the school changes something, not because it needs rescuing.
Stack
Flutter and Dart, talking to the school's systems over a small REST layer. PDF parsing does the unglamorous heavy lifting.