The idea of this typeface is to be geometric, elegant, with a vintage feeling, for use at larger sizes. It is inspired by geometric sans serif designs from the 1920s. The x-height is half way from baseline to cap height, an unusual proportion.
There is a sister family, Josefin Slab
In December 2019, it was updated with a Variable Font "Weight" axis.
To contribute, see github.com/googlefonts/josefinsans.