AP³M is an adaptive particle-particle, particle-mesh code. It is older than Hydra (ascl:1103.010) but faster and more memory-efficient for dark-matter only calculations. The Adaptive P³M technique (AP³M) is built around the standard P³M algorithm. AP³M produces fully equivalent forces to P³M but represents a more efficient implementation of the force splitting idea of P³M. The AP³M program may be used in any of the three modes with an appropriate choice of input parameter.