The present disclosure relates to systems, methods, and computer-readable media for managing routing of traffic between clients and resource instances when providing stateful services. For example, systems disclosed herein involve a load balancer that routes probe request(s) from clients to corresponding resource instances having access to stateful session data for a stateful session between the resource instance(s) and corresponding client(s). The resource instances may provide instance identifiers to the clients for use in generating subsequent session calls. In this way, systems described herein ensure that subsequent session calls are passed to the correct resource instances having access to relevant session information.