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🌌 Julia Set Generator

Generate Julia set fractals in real time. Drag the real and imaginary sliders for the constant c, pick a famous preset, and watch the fractal reshape instantly.

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GUIDE

Learn more

01

What is a Julia set?

For a fixed complex constant c, the Julia set is the set of starting points z for which the iteration z β†’ zΒ² + c stays bounded forever. Every value of c produces a completely different fractal. When c lies inside the Mandelbrot set the Julia set is a single connected shape; when c lies outside, it shatters into a scattered dust of infinitely many disconnected points.
02

The link to the Mandelbrot set

The Mandelbrot set is effectively the atlas of all Julia sets: each point on it corresponds to one Julia set, and whether that Julia set is connected or dust is decided by which side of the Mandelbrot boundary c falls on. Moving the real and imaginary sliders here is exactly like walking a pointer around that map β€” nudge c across the boundary and you watch a solid fractal dissolve into dust and back.
03

Tips for great fractals

Julia sets are extremely sensitive: a tiny change in c can transform the shape completely, so drag the sliders slowly and explore near the edges. Raise the iteration count to sharpen fine filaments and boundary detail, and lower it for a faster, softer render. Try the presets β€” Spiral, Dendrite, Galaxy and Lightning each sit at a famous value of c. When you find one you love, click Save PNG to export it at full resolution.

Frequently asked questions

What do the two sliders do?
They set the real part (a) and the imaginary part (b) of the constant c = a + bi. That single complex number defines the entire Julia set, so moving either slider reshapes the whole fractal.
Why did the fractal break into dust?
You moved c outside the Mandelbrot set. Outside that region the Julia set is no longer connected β€” it becomes a cloud of infinitely many separate points known as Fatou dust. Nudge c back toward the center to make it connected again.
How is this different from the Mandelbrot set?
The Mandelbrot set varies c while always starting z at 0, producing one master image. A Julia set does the opposite: it fixes c and varies the starting point z across the plane. Each point of the Mandelbrot set corresponds to one Julia set.