Feasible primer pair output. Feasible primer pairs are output: a) URPD provides a ranked primer pair output. The best primer set is always shown first. b) NCBI blast further enhances the specificity against the genome. c) Secondary structures of primers are clearly marked. d) The visualization shows the position of a primer pair and product information in a template sequence in color. e) A practical gel electrophoresis upload function is also available for comparison to virtual gel electrophoresis.