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Leonardo

Leonardo is a free, open-source tool for creating and managing accessible color systems for interface design and data visualization.

Place
#16 of 34
Score
6.0
Leonardo's website

What Leonardo is

Leonardo is a free, open-source tool for creating and managing accessible color systems for interface design and data visualization. It can generate swatches from target contrast ratios or target lightness, and adaptive themes let users adjust brightness, contrast, and saturation. For charts, it provides sequential and diverging color scales. Accessibility tools cycle through colorblind-safe palettes and compare color differences across color vision deficiency types; the web application also includes charts and 3D models for evaluating themes. Users can download themes and scales as SVG files, with Tableau XML and SVG export options for scales. Developer output includes parameters for @adobe/leonardo-contrast-colors, CSS custom properties, and design tokens. The JavaScript package is installed with npm and has examples for vanilla JavaScript and React. Leonardo also documents an MCP server for theme generation, contrast checks, color conversion, and palette creation. The project uses the Apache V2 license. Generated contrast ratios may be slightly higher than requested because of RGB color availability and color-space interpolation.

Good

  • Generates swatches by contrast ratio or lightness
  • Provides adaptive themes and chart color scales
  • Includes color-vision accessibility tools
  • Exports SVG, Tableau XML, CSS, and design tokens
  • Free and licensed under Apache V2

Watch out

  • Generated contrast ratios may exceed requested values

Who it suits

Leonardo suits designers and engineers building color scales for user interfaces, as well as people preparing data visualizations. Developers can use its package, outputs, and API-facing tools in their workflows.

Verdict

Leonardo brings palette creation, accessibility evaluation, and developer outputs together in a free, open-source project. Keep in mind that generated contrast values may not match the target exactly.

Plans and prices

From Leonardo's own pricing page, checked 9 Oct 2026.

All about pricing
PlanPriceWhat it gives you
Free / open sourceFreeNo paid plans or usage limits are stated on the opened pages

The facts

Each one read from Leonardo's own pages, with the date it was checked.

What it does

Adaptive themes
Adaptive themes let users adjust brightness, contrast, and saturation.checked 9 Oct 2026
AI tooling
The site documents an MCP server with tools to generate themes, check contrast, convert colors, and create palettes.checked 9 Oct 2026
Audience
The project describes its web application as a collaborative tool for designers and engineers building color scales for user interfaces.checked 9 Oct 2026
Color accessibility
The tools can cycle through colors for colorblind safe palettes and compare color difference across color vision deficiency types.checked 9 Oct 2026
Color analysis
The web application includes charts and 3D models for evaluating color themes.checked 9 Oct 2026
Contrast based colors
It generates color swatches from target contrast ratios and also lets users define swatches by target lightness.checked 9 Oct 2026
Data visualization
Leonardo offers sequential and diverging color scales for data visualization.checked 9 Oct 2026
Developer output
Theme output includes parameters for @adobe/leonardo-contrast-colors, CSS custom properties, and design tokens.checked 9 Oct 2026
Exports
Themes and color scales can be downloaded as SVG files, and the tool offers Tableau XML and SVG exports for scales.checked 9 Oct 2026
Integrations
The package documentation includes examples for vanilla JavaScript and React, and the homepage says its output can be copied into design tools.checked 9 Oct 2026
JavaScript package
The @adobe/leonardo-contrast-colors package can generate adaptive contrast-based colors and is installed with npm.checked 9 Oct 2026
License
The project is licensed under Apache V2.checked 9 Oct 2026
Limit
Generated contrast ratios may be slightly higher than the requested ratio because available RGB colors and color space interpolation constrain exact values.checked 9 Oct 2026
Purpose
Leonardo creates, manages, and shares accessible color systems for user interface design and data visualization.checked 9 Oct 2026

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