In some embodiments, a client application at a client device can receive, from a browser application at the client device, a first message including a unique identifier associated with a session of the browser application at a website associated with a content management system. The client application can extract the unique identifier from the first message, and establish a connection between the client application and the content management system by sending, from the client application to the content management system, a second message including the unique identifier. The client application can then receive, from the content management system through the connection, a third message relayed by the content management system from the website, where the third message is associated with the unique identifier.