MOTIVATION: Polymerase chain reaction (PCR) has been a revolutionary biomedical advancement. However, for PCR to be appropriately used, one must spend a significant amount of effort on PCR primer design. Carefully designed PCR primers not only increase sensitivity and specificity, but also decrease effort spent on experimental optimization. Computer software removes the human element by performing and automating the complex and rigorous calculations required in PCR primer design. Classification and review of the available software options and their capabilities should be a valuable resource for any PCR application. RESULTS: This article focuses on currently available free PCR primer design software and their major functions (https://pcrprimerdesign.github.io/). The software are classified according to their PCR applications, such as Sanger sequencing, reverse transcription quantitative PCR, single nucleotide polymorphism detection, splicing variant detection, methylation detection, microsatellite detection, multiplex PCR and targeted next generation sequencing, and conserved/degenerate primers to clone orthologous genes from related species, new gene family members in the same species, or to detect a group of related pathogens. Each software is summarized to provide a technical review of their capabilities and utilities.