DnaSP 6.12.3 could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this software available. We recommend checking the downloaded files with any free antivirus. The program is categorized as Education Tools.
The following versions: 6.0, 5.1 and 5.0 are the most frequently downloaded ones by the program users. This PC software works fine with 32-bit and 64-bit versions of Windows XP/Vista/7/8/10/11. This free program is a product of Universitat de Barcelona. The common filenames for the program's installer are dnasp5.exe, DNA-WT.exe, dnasp4.exe or DnaSP6.exe etc.
From the developer:
DnaSP, DNA Sequence Polymorphism, is a software package for the analysis of nucleotide polymorphism from aligned DNA sequence data. DnaSP can estimate several measures of DNA sequence variation within and between populations (in noncoding, synonymous or nonsynonymous sites, or in various sorts of codon positions), as well as linkage disequilibrium, recombination, gene flow and gene conversion parameters.
You may want to check out more software, such as TerraExplorer, ChemCAD or GraphCalc, which might be related to DnaSP.