I am looking at this website. It's called "Seasonax" seems to have a lot of functionality. Does anyone use it?

https://www.seasonax.com/

Yes, I've used Seasonax.

It's a good resource, and fairly priced. There's a lot of useful data for swing trading and investing but it is an adjunct to fundamental and technical analysis -not a replacement.

The problem I have with all seasonal analysis is that the data set is small. "100 years of data" is really just 100 data points. One should be careful not to draw firm conclusions from that. But perhaps this is a little unfair; it's not intended as a primary decision-making tool and overall it's worth trying out.