UNAFold 3.8 was available to download from the developer's website when we last checked. We cannot confirm if there is a free download of this software available.
We cannot guarantee that the program is safe to download as it will be downloaded from the developer's website. Before launching the program, check it with any free antivirus software. The most popular versions of the UNAFold are 3.8, 3.7 and 3.6. UNAFold is included in Development Tools. The actual developer of the software is Rensselaer Polytechnic Institute.
From the developer:
UNAFold is a comprehensive software package for nucleic acid folding and hybridization prediction. The name is derived from "Unified Nucleic Acid Folding". Folding of single-stranded RNA or DNA, or hybridization between two single-strands, is accomplished in a variety of ways. Partition functions can be computed to derive base pair probabilities and stochastic samples of foldings or hybridizations.
You may want to check out more software, such as OligoArrayAux, which might be related to UNAFold.