Opak Sans is a re-shaped version of Intel's 'Clear Sans' (designed by Dan Rhatigan & Monotype (https://01.org/clear-sans)).
Opak Sans has been paired down and adjusted on the Gnu+Linux desktop to work well with the Freetype font render engine. The Opak fonts are released under the Open Font License with full and free access to the project's fonts and source files via Github.