Primer3Plus Pick primers from a DNA sequence.
DimerChecker Check the possible primer dimers and hairpins
AutoDimer Rapidly screen PCR primers for primer-dimer and hairpin interactions.
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Secondary structure folding:
RNAfold web server Predict secondary structures of single stranded RNA or DNA sequences.
RNAstructure For RNA and DNA secondary structure prediction and analysis.
RNAsoft Software for RNA/DNA secondary structure prediction and design
