Chaotica is free for noncommercial use, and can render up to 1.23 megapixel images (e.g. 1280x960 resolution) and up to 30 second 480p animations without a licence.
A Chaotica HD licence for casual users who want to create high quality desktop wallpapers up to 4 megapixels (e.g. 2560x1600) and 720p animations up to 3 minutes long is available at a very low price point.
The professional Chaotica Studio licence has no still image or animation limitations at all.
If you are interested in purchasing a licence please visit the Glare Technologies Store:
https://store.glaretechnologies.com/chaotica (Euros) or
https://store.glaretechnologies.com/chaotica?currency=USD (US Dollars)
Download links:

Microsoft Windows
Installer: chaotica_x64_v2.0.36.msi
Archive: chaotica_x64_v2.0.36.7z

Mac OS
Installer: Chaotica_2.0.36.pkg

Linux
Archive: chaotica_x64_v2.0.36.tar.gz