Senior Full-Stack Developer for IoT Kids Audio Platform

About the Project:
We are building Wizmo, a screen-free audio platform for children (ages 3–10).
The system includes:
- A connected audio hardware player
- Physical content cards
- A parent companion app used only for setup and control
- A shared backend platform that powers identity, devices, content, and rules
Children never use screens.
Parents use the app only to pair devices, configure rules, and manage content.
Scope of Work (This Role)
This is a backend-first role.
You will not be responsible for building a full consumer app UI.
Primary Responsibilities
Design and implement backend APIs for:
- Parent authentication & sessions
- Child profiles & device registry
- Secure device pairing & ownership
- Content metadata (cards, permissions)
- Parental rules (time, volume, modes)
- Design offline-tolerant sync between device and backend
- Support session continuity between app and website
- Build internal/admin APIs to supp...