Has anyone used a free compounding calculator with Hazel?

Hi everyone,

I've been trying to automate something pretty specific. Every month I generate savings tracking files by exporting CSVs from my banking app, and I'd like Hazel to automatically run a compound interest calculation whenever a new file lands in a specific folder. Ideally, it would use either a free compound interest calculator or a local script, so the whole process runs without any manual steps.
I'm just not sure what the cleanest way to tie everything together is. I know Hazel can trigger a shell script, so that's probably the starting point. Has anyone here built a similar workflow using an external compound interest calculator? I'm debating whether to write a small Python script or call a web-based calculator with curl.
If you've already set up something like this and it's been reliable, I'd really appreciate hearing how you approached it.

Seems like that kind of logic can be implemented in a local script and python would be good as anything for that.