How do you secure APIs using API keys and OAuth?

Short answer: API Keys: Generated per subscription, required in request headers or query parameters. OAuth 2.0: APIM can validate bearer tokens issued by Azure AD or external IdP. Example – API key header: GET Header: Ocp-Apim-Subscription-Key: <your-subscription-key>

Real-world example (ShopNest)

ShopNest on Azure typically uses App Service + SQL Database + Blob Storage + Application Insights for monitoring.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.