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iWantHue vs Leonardo: catalog facts
iWantHue	Leonardo
Best for: Data scientists choosing colors for charts with many categories	Best for: Designers and developers building accessible color systems for interfaces and charts
Free Free to use, with source code on GitHub.	Free Free to use in the browser, with source published on GitHub.
Web	Web
Produces perceptually distinct colors Colorblind-friendly option All 4 strengths for iWantHue Produces perceptually distinct colors Colorblind-friendly option Exports to JSON, CSS and JavaScript in several color spaces Can correct or complete an existing palette	Generates swatches from target contrast ratios Adaptive themes make dark mode variants quick All 4 strengths for Leonardo Generates swatches from target contrast ratios Adaptive themes make dark mode variants quick Exports CSS custom properties, Design Tokens and SVG Separate tools for data visualization scales
Aimed at categorical data colors, not brand or UI palettes Colorblind optimisation is slow	Aimed at design systems work, more than a simple palette picker needs Contrast-driven approach takes some learning
Web application	Web application
Not open source	Open source
License not stated	License not stated
No account needed	Not stated if an account is needed
Needs internet	Not stated if it works offline
Official website Full listing and sources Sources for iWantHue medialab.github.io/iwanthue Catalog checked September 24, 2026	Official website Full listing and sources Sources for Leonardo leonardocolor.io Catalog checked September 23, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.