Focus stacking software recommendations

Is focus stacking (taking multiple images with small depth of field and combining them to get a sharp image) using free software possible? When I took a few images and tried aligning them using Hugin it failed possibly due to lens breathing as the images are distorted when changing focus. Fotoxx was successful at alignment but produced a poor image (maybe I used the wrong mode as I used HDR). Fotoxx's system requirements also exceed what I have (16 GB memory) so I'd prefer to try something else if there is such software. Attached are the images I tried to focus stack and the poor (but correctly aligned) Fotoxx result obtained using downscaled versions of the last 5 images. Is it possible to use Fotoxx for alignment only and to use the alignment in other software?