A system, method, and computer program product are provided for configuration based coexistence routing. In operation, a coexistence router system receives data from one or more systems during a coexistence period of a data migration process where information is in process of being migrated from one or more migration source systems to one or more migration target systems. The coexistence router system identifies one or more routing keys included with the data capable of being used to determine whether the data is associated with the one or more migration target systems or the one or more migration source systems. The coexistence router system queries a migration master database to determine whether the data is associated with the one or more migration target systems or the one or more migration source systems, based on the one or more routing keys. Furthermore, the coexistence router system routes the data to the one or more migration target systems or the one or more migration source systems based on the determination of whether the data is associated with the one or more migration target systems or the one or more migration source systems.