Zuul is a free and open-source application gateway written in Java that provides capabilities for dynamic routing, monitoring, resiliency, security, and more.
Amazon API Gateway is a fully managed service that makes it easy for developers to create, publish, maintain, monitor, and secure APIs at any scale. Supports RESTful APIs and WebSocket APIs (bi-directional communication between client and server).
Google Cloud Platform API Gateway enables you to provide secure access to your services through a well-defined REST API that is consistent across all of your services, regardless of service implementation. For full documentation follow this link.
API Management helps organizations publish APIs to external, partner, and internal developers to unlock the potential of their data and services.