Mine at the moment: Work Sans
Cooper Hewitt. Pentagram properly commissioned it before it was released as Open Source, and it shows.
Thanks man, been looking for something like this for a while!
ATM, Carrois Gothic. https://fonts.google.com/specimen/Carrois+Gothic
It's a friendly, condensed sans-serif with a nice set of small-caps. Only one weight, unfortunately.
Very nice font, thanks for sharing !
I love Overpass. It's very clear and powerful for its italic style. http://overpassfont.org
Alternative to Futura
I love Gravitas!
Kontrapunkt has a three high-quality free fonts. Not sure if they're open source, though.