Adobe Color CC - Generates color themes that can inspire any project.
COLOURlovers - COLOURlovers is a creative community where people from around the world create and share colors, palettes and patterns, discuss the latest trends and explore colorful articles... All in the spirit of love
Color hexa - Color hex encyclopedia providing information about any color.
Happy Hues - Curated color palettes in action
iWantHue - Colors for data scientists. Generate and refine palettes of optimally distinct colors.
ColorExplorer - Simply put, ColorExplorer is an online toolbox for working with color palettes.