The GraphQL specification defines three types of operations: Queries, Mutations, and Subscriptions. Subscriptions allow clients to subscribe to data changes, enabling real-time updates without polling the server. However, the specification does not specify a transport layer, leaving it up to individual implementations to choose between WebSockets, Server-Sent Events (SSE), or other protocols. This has led to five different implementations of GraphQL Subscriptions, each with its own strengths and weaknesses. To unify these implementations, WunderGraph is creating an API Gateway that supports multiple Subscription protocols, including WebSockets, SSE, and Apollo's subscription-transport-ws protocol. The gateway also provides a unified way to manage subscriptions, authentication, and filtering of messages. By standardizing on a "GraphQL Server capabilities" protocol, clients can easily determine which capabilities a GraphQL server has and which protocols it supports, enabling seamless communication between clients and servers. WunderGraph is an open-source solution that aims to simplify the complexity of GraphQL Subscriptions and provide a unified way to manage subscriptions across multiple APIs.