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Leonardo
What it is
Leonardo is a free, open-source web tool for creating, managing, and sharing accessible color systems for interface design and data visualization. It generates swatches from target contrast ratios or target lightness, and adaptive themes provide brightness, contrast, and saturation controls. For visualization, it offers sequential and diverging scales. Accessibility tools cycle through colorblind-safe palettes and compare color differences across color vision deficiency types. Charts and 3D models help evaluate themes. Themes can be downloaded as SVG, while scales support SVG and Tableau XML export. Developer output includes CSS custom properties, design tokens, and parameters for the @adobe/leonardo-contrast-colors package, which is installed with npm and documented for vanilla JavaScript and React. An MCP server is documented for generating themes, checking contrast, converting colors, and creating palettes. Leonardo also supports image color extraction, print color, CSV export, and accessibility checks. Generated contrast ratios may be slightly above requested values because of RGB and interpolation constraints.
For and against
For
- Free and open-source Apache V2 project
- Generates contrast- and lightness-based swatches
- Supports colorblind-safe palette checks
- Exports SVG, Tableau XML, CSS, and tokens
- Includes image extraction and print color
Against
- Contrast ratios may exceed requested values
- Browser-based web platform is listed
- No paid plans are stated
- Color tools remain focused on palette work
The verdict
Leonardo combines palette generation, accessibility review, adaptive themes, and developer-oriented exports. It is suited to teams moving color systems between design, visualization, and code workflows.
Who it suits
Leonardo suits designers and engineers building accessible interface palettes or data-visualization scales in a collaborative web tool.
Plans and prices
Free / open source
No paid plans or usage limits are stated on the opened pages
Read 9 Oct 2026 · github.com
On the record
- Adaptive themes
- Adaptive themes let users adjust brightness, contrast, and saturation.leonardocolor.io · read 9 Oct 2026
- AI tooling
- The site documents an MCP server with tools to generate themes, check contrast, convert colors, and create palettes.leonardocolor.io · read 9 Oct 2026
- Audience
- The project describes its web application as a collaborative tool for designers and engineers building color scales for user interfaces.github.com · read 9 Oct 2026
- Color accessibility
- The tools can cycle through colors for colorblind safe palettes and compare color difference across color vision deficiency types.leonardocolor.io · read 9 Oct 2026
- Color analysis
- The web application includes charts and 3D models for evaluating color themes.leonardocolor.io · read 9 Oct 2026
- Contrast based colors
- It generates color swatches from target contrast ratios and also lets users define swatches by target lightness.leonardocolor.io · read 9 Oct 2026
- Data visualization
- Leonardo offers sequential and diverging color scales for data visualization.leonardocolor.io · read 9 Oct 2026
- Developer output
- Theme output includes parameters for @adobe/leonardo-contrast-colors, CSS custom properties, and design tokens.leonardocolor.io · read 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.leonardocolor.io · read 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.leonardocolor.io · read 9 Oct 2026
- JavaScript package
- The @adobe/leonardo-contrast-colors package can generate adaptive contrast-based colors and is installed with npm.leonardocolor.io · read 9 Oct 2026
- License
- The project is licensed under Apache V2.github.com · read 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.leonardocolor.io · read 9 Oct 2026
- Purpose
- Leonardo creates, manages, and shares accessible color systems for user interface design and data visualization.leonardocolor.io · read 9 Oct 2026
