Nice project. Some comments/feature requests:

What is the tech stack? It it running in the browser or the server or both?

It's weird that if I click "Download Chart", I get the chart that I'm seeing, but a new chart is generated with new random colors.

Is it a good idea to randomize the colors in each interaction? I think I prefer fixed colors.

It would be nice that the "Generate Advanced Chart" button transfer the data from the basic version to the advanced version. I'm not sure how hard it is.

Have you considered an excel-like data grid for chart input? (Like

It would be more user friendly compared to the comma seperated lists in the input fields.

> visually stunning representations of their data

The Steve-Jobs-ification of describing how things look has gone too far.