SyntaxEnvy - random syntax highlighting themes
HSLuv is used in SyntaxEnvy to generate pleasing color palettes that have consistent contrast.
Color Studio - theme builder
Color Studio uses HSLuv to help you design dark UI themes.
Seaborn - statistical data visualization library
Seaborn uses HSLuv to generate color palettes for its charts.
Rebelle - watercolor and acrylic paint software
Rebelle uses HSLuv as one of its options in the color picker.