In a distributed system that includes a debug server and debug clients coupled for data communications through a data communications network, where the debug server includes a debug administrator, a message router, a back-end debugger, and a debuggee, collaborative software debugging includes receiving application-level messages, including receiving, a request to establish a chat session associated with a location in source code of the debuggee; routing the application-level messages among the debug clients, the debug administrator, and the back-end debugger; returning client-specific debug results, including sending, to the debug clients, a notification of an established chat session; and administering, by the message router, chat content for the established chat session among debug clients. Debug clients display the chat content in a chat box at the location in source code when the view of source code includes the location.