APOLLO3® is a French deterministic reactor code for lattice and core calculations. It has been developed at CEA (Commissariat à l’Energie Atomique) with the financial and technical support of EDF (Electricité de France) and Framatome since 2007. The main goal of APOLLO3 is to provide a unified deterministic tool that includes the capabilities of the French lattice and core codes of the previous generation, APOLLO2, CRONOS2, ECCO, and ERANOS, introducing many improvements to reactor physical modeling in a modern and flexible software architecture platform for research and development and industrial activities. This paper presents an overview of the main new capabilities of the APOLLO3 code in the lattice and the core components.