NEST FTTx is simulation software that models fiber-to-the-x (FTTx) optical access networks, enabling users to reproduce real-world operator networks. It provides tools for planning network architecture, optimizing equipment placement like concentrators, analyzing fiber connections from customers to central offices, and performing cost analysis. NEST FTTx supports technologies like GPON and point-to-point, uses GIS maps, and provides reports to facilitate network design and optimization.