Credits & Licences
The JUMI Colour Generator is built with open-source typefaces used under permissive licences, and implements several published colour-science models. Everything else — the colour-harmony algorithms, HSL and Oklab maths, WCAG contrast calculations, image quantiser, gradient builder and UI logic — is original code written by JUMI Ltd, with no third-party JavaScript or CSS frameworks. With gratitude to the authors below.
Typefaces
All three typefaces are served via Google Fonts and licensed under the SIL Open Font License 1.1, which permits free use, modification and redistribution in any software.
| Typeface | Used for | Designer & copyright |
|---|---|---|
| Manrope Specimen | Body copy and UI labels | Mikhail Sharanda. © 2018–2023 The Manrope Project Authors. |
| Space Grotesk Specimen | Headings and display text | Florian Karsten. © 2018–2021 The Space Grotesk Project Authors. |
| Space Mono Specimen | Hex codes, labels and exported code | Colophon Foundry for Google. © 2016 The Space Mono Project Authors. |
Colour science and published models
The tool implements the following published work directly. No third-party code is used; these are specifications, formulae and matrices we have implemented ourselves, credited here because the underlying research is not ours.
| Model | Used for | Source & terms |
|---|---|---|
| Oklab / OKLCH | Spacing the steps of the tonal-scale generator, gamut-mapping those steps back into sRGB without hue drift, and the OKLCH palette export | Björn Ottosson, "A perceptual color space for image processing" (2020). The reference implementation is released into the public domain. |
| Colour vision deficiency matrices | The protanopia, deuteranopia and tritanopia simulations in Vision check | G. M. Machado, M. M. Oliveira & L. A. F. Fernandes, "A Physiologically-based Model for Simulation of Color Vision Deficiency", IEEE Transactions on Visualization and Computer Graphics, 15(6), 2009. |
| Rec. 709 relative luminance | The achromatopsia simulation and the contrast-ratio calculation | ITU-R Recommendation BT.709, as incorporated into WCAG 2.1. |
| Median cut & Lloyd's algorithm (k-means) | Reducing an image to its dominant colours in the image-extraction panel | Classical algorithms in the public domain — median cut after Paul Heckbert (1982), k-means refinement after Stuart Lloyd (1957/1982). Implemented from the published descriptions. |
Accessibility standard
The contrast-ratio formula and the WCAG pass/fail thresholds used in the contrast checker are derived from the Web Content Accessibility Guidelines (WCAG) 2.1, published by the W3C Web Accessibility Initiative (WAI). WCAG is an open standard; the specification is freely available under the W3C Document License.
No other third-party code
The JUMI Colour Generator contains no npm packages, JavaScript frameworks, CSS frameworks or runtime dependencies beyond the browser itself. All colour science, palette-generation algorithms, the image quantiser, the vision simulator, the tonal-scale builder, the gradient builder, WCAG calculations, export formatters and UI rendering are original code written by JUMI Ltd, implementing the published models credited above.
Two browser APIs are used where available and skipped where not: the EyeDropper API powers the optional "Pick from screen" button in Chromium-based browsers, and the Canvas API decodes images locally for palette extraction. Neither sends anything anywhere.
Third-party names
"YOOtheme" is a trade mark of YOOtheme GmbH and "Tailwind CSS" is a trade mark of Tailwind Labs Inc. Both are referenced on this site only to describe compatibility features — a gradient export scoped for a YOOtheme Pro custom-CSS field, and a palette export shaped like a Tailwind colour configuration. JUMI Ltd is not affiliated with, sponsored by or endorsed by either company. See Terms of Use, section 12.
Services
- Google Fonts — typefaces are loaded from Google's font CDN. See the Google Fonts privacy FAQ for what data is processed.
- Google Analytics 4 — used with your consent to understand aggregate, anonymous usage, with IP anonymisation enabled. See our Privacy Notice.
- Google AdSense — the advertising platform that will fund the tool. Not currently active on this site; see our Cookie Policy.
Intellectual property
The JUMI Colour Generator name, logo and all original source code are © JUMI Ltd 2026. All rights reserved. The open-source components listed above remain the intellectual property of their respective authors and are used in accordance with their licences.
Related: Terms of Use · Privacy Notice · Copyright Policy