Site Palette - Get the essential colours from any website
accessiBe - Making websites accessible to people with disabilities
Color Palette Generator - Enter the URL of an image and find its color palette
Page Speaker - Modern web accessibility tools for agencies & webmasters
Colour Contrast Analyser - TPGi's ADA Color Contrast Checker checks for helps determine the accessibility the contrast ratio of two colors for WCAG AA and AAA.
Koa11y - Automatically detect accessibility (a11y) issues on webpages