This paper describes and compares the numerical techniques for computing the Neutral Beam Injection (NBI) physics used in NBI modules in several integrated modeling codes. The Monte-Carlo NUBEAM module and the Fokker–Planck NBI ASTRA, DBEAMS, FPP, and NBEAMS neutral beam injection modules are considered. Physics included in these modules is discussed. Resulting electron and ion power heating profiles and particle source profiles for the TFTR discharge 66887 and the JET discharge 52009 are compared when computed with the NUBEAM, NBI ASTRA, DBEAMS and FPP modules.