What is the purpose of an API proxy?

• A. It runs on the client device
• B. It controls access to a web service and restricts usage via an API gateway
• C. It stores data in a data warehouse
• D. It formats responses for UI rendering only

Answer: (B)

An API proxy sits as the gatekeeper in front of an API, mediating all calls between clients and the backend service. Its primary job is to control who can access the API and how much they can use it. By routing traffic through a proxy, you can enforce security policies (like authentication, authorization, OAuth, and API keys), implement rate limits and quotas, throttle abusive traffic, and monitor usage. It also helps hide backend details and provides a single, governed entry point via the API gateway.

This role isn’t about running on the client, storing data, or merely formatting responses for a UI. Those aspects aren’t the proxy’s main function. The core purpose is governance: controlling access and usage through the gateway.