In my final year of university, I was on the committee for my college's biennial ball. In my position as webmaster and head of ticketing, I built a Django based ticketing website with Stripe integration which allowed for easy ticket purchasing for over 1400 guests with page response times of under 10ms at peak load. For entry on the door I connected six barcode scanners to Nexus 7 tablets using USB OTG running a custom Android application and connected to a local network to allow entry using NFC and barcoded tickets. My system halved the total time taken to admit our guests.
Django and Android.