ColorBox

ColorBox is a free open-source color tool by Lyft Design — designed to help designers create accessible color systems by generating color scales with control over hue + saturation + lightness curves. Different from random palette generators (Coolors) and curated palette galleries (Color Hunt, Branition Colors), ColorBox is for designing the systematic color ramps that power modern design systems — the 50-100-200-300-...-900 scales you see in Material Design + Tailwind + IBM Carbon. What you get: visualize color scales as ramps, control hue + saturation + lightness curves independently for the scale (linear curve, easing curves, custom adjustments), generate ramps in multiple base hues simultaneously (for a full design-system color set), preview colors on light + dark backgrounds, accessibility contrast preview, export as HEX values or design tokens. The killer feature is the curve control — most palette generators give you discrete color picks, but design systems need ramps where the steps progress smoothly. ColorBox gives you that. Where ColorBox fits: Tailwind's default color palette + Material's color tools + Refactoring UI's color advice are all built on the same idea — systematic color ramps with controlled curves. ColorBox is the standalone tool for designing your own ramps. Alternatives: Leonardo by Adobe (similar but more advanced contrast-driven generation), Tailwind Color Generator (uicolors.app — Tailwind-specific palette generation), HSLuv color picker (for perceptually-uniform color), and ColorBox is one of the originals from the same era as Material's color tool. Where it's not for you: if you want individual palettes (5-color schemes, brand palettes), use Coolors or Branition Colors. If you want Tailwind-specific palette generation with shadcn-style output, uicolors.app is purpose-built. If you want contrast-driven accessibility ramp generation, Leonardo by Adobe is more advanced. If you just need a few colors for a one-off project, ColorBox is overkill — it's for systematic color design. Pricing: free, open source. Lyft funded development as part of their public design system contributions. Honest take: if you're building a design system from scratch and you want to design your own color ramps (rather than copying Tailwind's defaults), ColorBox is one of the right tools to learn. The curve-based approach forces you to think about color systematically — how does saturation change across the ramp? Does hue shift toward warmer or cooler as lightness decreases? These are the questions ColorBox lets you answer visually. For one-off projects, overkill; for design system foundations, essential.