The software is built to calculate multi-component diffusion of ions over a user defined domain based on the equations of previous workers which are summarized in Oelkers (1996). These equations account for charge balance and the derivative of the species activity coefficient with respect to changes in concentration. It uses a simple, fully explicit finite difference approximation to calculate diffusion profiles and has been compared to a previous benchmark used by other software packages (Rasouli et al., 2015). The software is capable of simulating three different boundary conditions at the left boundary: closed, closed with a constant CO2 concentration, and constant. The right boundary is always closed. One can also apply a temperature gradient over the domain, though the software has not been tested against a Soret effect benchmark.