Certain aspects and features of the present disclosure relate to systems and methods for automatically classifying hosts in real-time. For instance, classifying hosts as bots, and subsequently mitigating or blocking traffic from the hosts classified as bots can be advantageous in real-time data exchange systems. In a real-time data exchange system, data can be exchanged between a server and a target host in real-time when the target host accesses a webpage. Inhibiting data communication between servers and hosts operated by bot scripts can reduce fraudulent activity. In some implementations, hosts can be automatically classified into various groups based at least in part on the data included in requests received from the hosts.