There is an increasing demand for real-time data delivery as users expect faster experiences and instantaneous transactions. This requires not only lower latency per message but also the ability to handle far greater capacity in a globally-distributed manner. To address these requirements, WebSocket has become the dominant protocol for real-time web applications, offering persistent, fully-duplexed connections to achieve low latency requirements. Publish/Subscribe (pub/sub) has been around longer and enables providers to scale data transmission systems dynamically, which is crucial for providing new capacity needs. A simple pub/sub service can be built with WebSocket and Redis, but at scale, additional complexities such as message persistence, horizontal scaling, disaster recovery, and authentication need to be addressed. Ably provides a globally distributed pub/sub service that handles these difficulties, offering a comprehensive, managed Pub/Sub solution that allows developers to focus on their core application without the overhead of managing complex infrastructure.