primer3

Primer3 helps to choose primers for PCR reactions

"Primer3 is a complete rewrite of the original PRIMER program (Primer 0.5), written by Steve Lincoln, Mark Daly, and Eric Lander. See DIFFERENCES FROM EARLIER VERSIONS for a discussion of how Primer3 differs from its predecessors, Primer 0.5 and Primer v2. Primer3 picks primers for PCR reactions, considering as criteria: o oligonucleotide melting temperature, size, GC content, and primer-dimer possibilities, o PCR product size, o positional constraints within the source sequence, and o 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." - from the README file