fragcoord.xyz

Huh:

FragCoord is a real-time GLSL fragment shader editor. Write shader code on the left, see the result rendered instantly on the right. No setup required — just start typing.

That’s from the docs that explains how this website is Codepen but for shaders. Each example is hypnotic and fun but from a totally different universe where math and art were always the same class in high school.

There’s a lot of interesting interface ideas going on here, too. Being able to select, inspect, and tweak variables, etc. It’s all slick and neat and weird.