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Fractal & L-System Generator

Draw fractal trees, ferns, Koch snowflakes, dendrites, Hilbert curves and Sierpinski triangles. Explore iterations and angles, write custom branching rules and export SVG or PNG.

Local processingExamples includedSVG / PNG where applicable

1. Set up your creation

Open saved settings

Custom production rules · one per line (used in Custom mode)Open UTF-8 text file

F and G draw forward, f moves without drawing, +/− turn and [/] save/restore branches. Other letters are rewriting variables. Rules are simultaneous and deterministic. A 200,000-symbol cap prevents runaway expansions.

2. Preview & use the result

Load an example to get started.

Preview size

Complete text result / calculation details

Changing settings disables old exports. Processing runs locally; website ads and analytics follow our privacy information.

Using Fractal & L-System Generator

Draw fractal trees, ferns, Koch snowflakes, dendrites, Hilbert curves and Sierpinski triangles. Explore iterations and angles, write custom branching rules and export SVG or PNG.

Choose a preset; its suggested angle and iteration count load automatically. Generate and explore the result.
Adjust iterations, angle, stroke and colors. Custom mode uses your axiom and one-character production rules.
Inspect the fitted drawing and segment count. Export SVG, PNG or the complete settings report.

Example

F and G draw forward, f moves without drawing, +/− turn and [/] save/restore branches. Other letters are rewriting variables. Rules are simultaneous and deterministic. A 200,000-symbol cap prevents runaway expansions.

Questions & answers

What is an L-system?

A starting string is rewritten using production rules for several iterations. A turtle then interprets drawing, turning and branching commands to produce the image.

Can I write my own rules?

Yes. Choose Custom and write rules such as F=F[+F]F[-F]F. Each rule has one letter on the left. JavaScript and arbitrary code are not evaluated.

Why can more iterations stop?

The expansion is limited to 200,000 symbols, eight iterations and 200 nested branches. Reduce iterations or simplify the rules if a limit is reached.

Are these images usable outside the site?

They are generated mathematical drawings. Download SVG for scalable paths or PNG for the current raster appearance; settings reports help reproduce them.

Is my input uploaded for processing?

No processing upload is used. This tool runs in a local browser worker. Website ads and analytics follow the site privacy information.