https://www.optimo.ch/typefaces_Plain.html

Every word could be a logotype. Text composes effortlessly balanced lines. It works from footnote to poster size. The graphic aesthetic is unique yet universal.  Few typefaces have qualified to this level of visual alchemy, epitomized by the classic Helvetica from the photo lettering times.  If Plain is so fluid, it is thanks a drawing that is neither constrained by a geometrical approach nor structured after the idiosyncrasy of the stroke. Glyphs are designed optically, as plain surfaces and, under an apparent modern simplicity, their dynamic interaction create a distinctive identity. Plain is the achievement of years of research by François Rappo, whose Theinhardt family had set a milestone in revisiting Grotesque typeface design. It comes in an exceptionally large range of twelve weights and their matching italic, offering graphic designers a complete tool to make the best use of its potential.