What Is an API Gateway?
API gateway takes all API calls from clients, then routes them to the appropriate backend service with request routing, composition, and protocol translation. API gateway secures, protects, manages, and scales API calls by intercepting API requests and applying policies such as throttling and security using handlers and managing API statistics.
Upon validation of applicable policies, the API gateway passes API client requests to the service implementing backend. The operation of an API gateway is very similar to an enterprise service bus (ESB).