Hemera is the name of Jane Crocker's browser of choice, and it is revealed that it is also the name of the Denizen of her land, the Land of Crypts and Helium. Hemera is likely to be the Denizen associated with Life, and thus presumably also Feferi's denizen in the Land of Dew and Glass. The same way John's color matched Jade's browser and vice-versa, Hemera's color matches Dirk's.
In Greek mythology, Hemera is the primordial goddess of daytime.
Hemera also appears to be half of UU's caduceus chat symbol, when combined with the other denizen, Nyx.