Kidoo

The problem

Classrooms lose signal. Staff still need to mark children in and out, and two phones must never clash on the same child.

What I built

• NestJS API on PostgreSQL, Redis and MinIO, packaged in Docker on a private VPS
• Offline first staff app: changes wait on the phone, then sync in order when signal returns
• Passkey sign in for staff and admins instead of passwords
• Grafana, Prometheus and Sentry so problems show up before users report them