primer3 - 2.6.1-4 main

Primer3 picks primers for Polymerase Chain Reactions (PCRs), considering as
criteria oligonucleotide melting temperature, size, GC content and
primer-dimer possibilities, PCR product size, positional constraints within
the source sequence, and miscellaneous other constraints. All of these
criteria are user-specifiable as constraints, and some are specifiable as
terms in an objective function that characterizes an optimal primer pair.