siRNA's, or short interference RNAs, are widely used in biological model systems to inactivate genes of interest. Recently, a plasmid based RNAi system has emerged based on a DNA vector called pSUPER. However, designing primers to make the pSUPER constructs can be an error prone and time-consuming task. Therefore, we made iRNAi, a tool to help scientists quickly design error free oligos.