Here's a nice epidemic calculator
I want to know how it was created.
I know it's possible to do something similar with python/dash.
Looking at the source code, it might have been created with svelte.
Is there anything else? Or is svelte enough?
There are credits for this app, why don't you ask the author ?
But yes, it's a Svelte APP, the sources are here : https://github.com/gabgoh/epcalc