Is this open source? I don't see a link anywhere. Would love to know the graph rendering works.

It is open source, here is the link: https://github.com/mendableai/firegraph

We use this awesome library to render the graphs: https://www.tremor.so/

This is well excited. I don’t know what’s the use case, is it just create a graph and download image?

I’ve used a similar service before to generate graphs on the fly in order to use them inside PDF. It made prototyping quick and easy

That is right! Create a graph and export an image, could be used for any number of things like tweets, presentations, etc