Just learned that my little visual cosine gradient generator tool (from 2015) is featured in this popular video tutorial (1.1M+ views) about artistic shader programming:
https://youtu.be/f4s1h2YETNY?t=971
The tool is still here:
https://dev.thi.ng/gradients/
If you want to use these gradients outside shaders (e.g. for dataviz purposes), the actual gradient functionality is also included in these two libraries:
https://thi.ng/color (TypeScript/JavaScript)
Related readme section with presets and code examples:
https://github.com/thi-ng/umbrella/blob/develop/packages/color/README.md#cosine-gradients
Clojure/ClojureScript version:
https://github.com/thi-ng/color/blob/master/src/gradients.org