SuSeFLAV 1.2: Program for supersymmetric mass spectra with seesaw mechanism and rare lepton flavor violating decays. Accurate supersymmetric spectra are required to confront data from direct and indirect searches of supersymmetry. SuSeFLAV1 is a numerical tool capable of computing supersymmetric spectra precisely for various supersymmetric breaking scenarios applicable even in the presence of flavor violation. The program solves MSSM RGEs with complete 3×33×3 flavor mixing at 2-loop level and one loop finite threshold corrections to all MSSM parameters by incorporating radiative electroweak symmetry breaking conditions. The program also incorporates the Type-I seesaw mechanism with three massive right handed neutrinos at user defined mass scales and mixing. It also computes branching ratios of flavor violating processes such as View the MathML sourcelj→liγ, View the MathML sourcelj→3li, View the MathML sourceb→sγ and supersymmetric contributions to flavor conserving quantities such as (gμ−2)(gμ−2). A large choice of executables suitable for various operations of the program are provided.