FreeON is an experimental, open source (GPL) suite of programs for linear scaling quantum chemistry. It is highly modular, and has been written from scratch for N-scaling SCF theory in Fortran95 and C. Platform independent I/O is supported with HDF5. FreeON should compile with most modern Linux distributions and OS X. FreeON performs Hartree-Fock, pure Density Functional, and hybrid HF/DFT calculations (e.g. B3LYP) in a Cartesian-Gaussian LCAO basis. All algorithms are O(N) or O(N log N) for non-metallic systems. Periodic boundary conditions in 1, 2 and 3 dimensions have been implemented through the Lorentz field (Γ-point), and an internal coordinate geometry optimizer allows full (atom+cell) relaxation using analytic derivatives. Effective core potentials for energies and forces have been