Cal Sans is a geometric sans-serif tuned for display, that is, large point sizes. It is an Open Source typeface to adorn the headlines and interfaces of Cal.com, a company founded by Peer Richelsen and Bailey Pumfleet and interface design by Ciarán Hanrahan.
As this design was created for display, and is currently a single static font, an unusual approach is taken for its texture and default typography. Letters are intentionally spaced to be extremely close for tight headlines “out of the box.” For smaller subheadings, positive letter spacing must be applied. There are currently no other Open Source geometric sans serifs geared as intentionally for “tight but not touching” typesetting—as it is more labor intensive to produce with accurate texture. But for typesetters, if they would letterspace another design as tight as Cal Sans, the results would not be as consistent.
In celebration of Futura’s geometrically extreme ligatures, Cal Sans has an experimental approach to ligatures, Stylistic Set 02 (ss02) is identical to ss01, but also combines eligible letters as historical Futura ligatures. This is included as a stylistic set and not as discretionary ligatures because default characters really do not match these historical ligatures.
Probably the most novel OpenType feature of Cal Sans is its third Stylistic Set (ss03). The best way to exhibit the need of ss03 is to see how “tight but not touching” affects spacing with consecutive diagonals. Some designers would never want their letters to overlap or touch in a headline, or very large title.