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Leonardo

leonardocolor.io

Free plan WebAPI
Visit leonardocolor.io
Spec score 7.5 #16 of 34 in Color Palette Generators

What it is

Leonardo is an open-source tool for creating, managing, and sharing accessible color systems for interface design and data visualization. Users can generate swatches from target contrast ratios or set target lightness, then adjust brightness, contrast, and saturation with adaptive themes. Sequential and diverging scales support data visualization. Accessibility tools can cycle through colorblind-safe palettes and compare color differences across color vision deficiency types, while charts and 3D models help evaluate themes. Themes and scales can be downloaded as SVG, and scales can also be exported as Tableau XML. Developer output includes parameters for @adobe/leonardo-contrast-colors, CSS custom properties, and design tokens. The related JavaScript package generates adaptive contrast-based colors and is installed with npm; its documentation includes vanilla JavaScript and React examples. The site also documents an MCP server for generating themes, checking contrast, converting colors, and creating palettes. The project is licensed under Apache V2 and has a free plan listed at free. One limitation is that generated contrast ratios can be slightly above requested values because RGB colors and color-space interpolation constrain exact results.

Spec sheet

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

Plans and prices

Free / open source Free No paid plans or usage limits are stated on the opened pages Read 9 Oct 2026 · github.com

Every Leonardo plan and price →

Strong points and limits

Strong points

  • Generates swatches from contrast or lightness targets
  • Includes sequential and diverging data scales
  • Color vision deficiency comparison tools
  • Exports SVG, Tableau XML, CSS, and design tokens
  • Free and licensed under Apache V2

Limits

  • Generated contrast ratios may exceed requested values slightly
  • Web app is the only listed platform
  • No paid plans are stated

Who it suits

Leonardo suits designers and engineers building accessible color scales for interfaces or data visualizations. Developers can also use its package and output formats in JavaScript, React, CSS, or design tokens.

Verdict

Leonardo covers color generation, accessibility checks, evaluation, and developer-oriented exports in a free open-source tool. Exact contrast targets may not always be achievable.

Where Specifiction places it

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