ABI Sequence Scanner – Free trace viewer. Allows you to look at ABI chromatograms and raw signals. Helpful for troubleshooting; only works for Windows.
Primer Design
Primer3 – Tool that helps you design primers automatically.
ExonPrimer – Automatically designs primers around your exons. Input reference sequence and cDNA sequence and the program outputs primers that flank the exons.
Tm Calculator – Automatically calculates the melting temperature of your primers.