Palette Ninja - Create harmonious color schemes
Colormind.io - A color palette generator powered by deep learning.
iWantHue - Colors for data scientists. Generate and refine palettes of optimally distinct colors.
Color Palette Generator - Enter the URL of an image and find its color palette
Image Color Summarizer - The web service provides statistics describing color characteristics of an image identified by URL.
Adobe Color CC - Generates color themes that can inspire any project.