The disclosed subject matter relates to a system for messaging between applications, the system having one or more processors and a memory including instructions that, when executed by the one or more processors, cause the one or more processors to perform operations including receiving a message including an identifier associated with a web application having a subscription to receive selected events associated with a publisher operating on a data network. The operations also include receiving, from the publisher, an event notification of at least one of the selected events. The operations also include determining whether the web application is subscribed to receive the event notification. The operations also include transmitting, in a case where the web application is subscribed to receive the event notification, an indication of the event notification to the web application.