Lufthamn Studio’s opensource (free) sans serif typeface. It would seem free fonts are becoming better. I believe free fonts are needed in sectors that just won’t pay for them. I look at it as a donation to the greater good. Everyone knows, most free fonts are garbage. This one is not.
Do check out SIL’s fonts as well. They’re the only organization I know of that has contributed fonts with such extended, sometimes obscure, character sets. I used SIL Doulos in The Typographic Desk Reference.