Examples of techniques for data sharing among processing systems in a collaboration group are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method includes receiving a message sent to a collaboration group via a first network connection. The first processing system is a member of the collaboration group. The method further includes downloading data associated with the message via the first network connection. The method further includes determining whether any additional processing systems that are members of the collaboration group are in proximity to the first processing system. The method further includes, based at least in part on determining that a second processing system that is a member of the collaboration group is in proximity to the first processing system, transmitting a message indicator from the first processing system to the second processing system via a second network connection.