UNAFold
From BioPerl
Michael Zuker's and Nick Markham's unified nucleic acid folding package [1] which now supersedes mfold.
It can be found here.
References
- Markham NR and Zuker M. DINAMelt web server for nucleic acid melting prediction. Nucleic Acids Res 2005 Jul 1; 33(Web Server issue) W577-81. doi:10.1093/nar/gki591 pmid:15980540.

