Color accessibility: tools and resources to help you design inclusive products by Stéphanie Walter - UX Researcher & Designer.
Color Contrast Analyzer
Fix Color Contrast – Web Accessibility for Text & UI Design - Pimp my Type
FixA11y — improving accessibility
The “dark yellow problem” in design system color palettes
Use Contrast
WCAG Color contrast checker
WCAG Color contrast checker - Microsoft Edge Addons
WCAG Contrast checker – Get this Extension for 🦊 Firefox (en-US)