At home we always ended up buying the same thing twice or getting to the shop without half the list. Paper notes and WhatsApp groups don't sync. So I built an app.
The idea
A shared, real-time shopping list: if my partner ticks off the milk from her phone, it disappears from mine instantly. Sounds simple, but "real time" is exactly where the technical meat is.
The stack
- Front: React Native + Expo — a single codebase for Android, shipped as an APK.
- Real time: WebSockets with Socket.io. Every change is broadcast to all devices connected to the same list.
- Backend: Node.js + Express, with MongoDB Atlas for persistence, auth and shared lists.
- Infra: deployed on my own NAS with Docker, Nginx as a reverse proxy, automatic SSL via Let's Encrypt and CI/CD with GitHub Actions + EAS Update.
What I learned
- Real-time state is easy to break. I had to think hard about reconciliation when two people edit at once and one drops connection.
- Self-hosting teaches more than any tutorial. Setting up Nginx, certificates and CI/CD for something you actually use forces you to understand the whole piece, not just the code.
- An app you use daily maintains itself — bugs show up in real use, not in demos.
For the technical breakdown (problem, architecture, results), see the project page.