API Gateway supports clustering to achieve horizontal scalability and reliability. The following figure illustrates an API Gateway cluster consisting of multiple API Gateway nodes.

Each API Gateway cluster node holds all the API Gateway components including UI, the API Gateway package running in webMethods Integration Server, and an Event Data Store(also known as Internal Data Store) instance for storing assets. A load balancer distributes the incoming requests to the cluster nodes. The synchronization of the nodes is performed through a Terracotta server array and Event Data Store clustering that is defined across the Event Data Store instances.

As each node of an API Gateway cluster offers the same functionality, nodes can be added or removed from an existing cluster. The synchronization of any new node happens automatically. The synchronization includes configuration items, and runtime assets like APIs, policies, and applications. The synchronized runtime assets become active automatically.