Manrope, by Mikhail Sharanda, is a free and variable sans serif font. It might be interesting for screen interface and fast load times, because it is a variable font.
Mikhail describes his font as:
This font is a crossover of different font types: it is semi-condensed, semi-rounded, semi-geometric, semi-din, semi-grotesque. It employs minimal stroke thickness variations and a semi-closed aperture. The fourth version of the font comes in a Variable Font format, and 7 legacy weights.