We recently produced allele frequency data for 20 forensic STRs in more than 50 worldwide populations. The STRs characterized include 5 new European Standard Set (ESS) STRs where novel low frequency and intermediate-repeat genotypes found were confirmed by sequence analysis. Data for the 20 STRs has been collated into an open-access online frequency browser at: http://spsmart.cesga.es/popstr.php that allows users to combine populations into groups to generate re-calculated allele frequency estimates from the merged genotype data. The flexibility to combine populations in this way and the graphical summaries provided for each marker's allele frequencies offers the forensic analyst an informative system to consult STR variability in a global range of populations.