More and more, computations are playing an important role in the theory and design of high intensities linacs. In this context, CEA Saclay is involved in several high power particles accelerators projects (SNS, ESS, IFMIF, CONCERT, EURISOL) and high intensities protons front end demonstrators (LEDA, IPHI). During these last years, several codes have been developed. This paper consists in a review of several of these codes especially: the linac generator able to design linac structures (computations coupled with SUPERFISH), the TOUTATIS code computing transport in RFQs in 3D grids (multigrid Poisson solver), the Trace Win code allowing to compute end to end simulation of a whole linac (automatic matching, up to 2 millions macroparticles run for halo studies with its PARTRAN module with 3D space charge routines, an errors studies module allowing large scale computations on several PCs using a multiparameters scheme based on a client/server architecture).