Secure Steam Inventory API Development

I need a backend API to fetch public Steam inventory data. The API should use my own proxy for rotation to avoid IP bans/rate limits and be secured with API Key and IP Whitelisting.

Requirements:
- Fetch public Steam inventory data reliably
- Use own proxy for rotation
- Secure private access (API Key with IP Whitelisting), with option for public exposure in future
- Store data in a NoSQL database (e.g., MongoDB, Cassandra)

Ideal skills and experience:
- Strong backend development experience
- Familiarity with Steam API
- Experience with NoSQL databases
- Knowledge of proxy rotation techniques
- Security implementation (API Key, IP Whitelisting)