SEO Website Question!

Hi, I'm trying to discover the best free tool or website which tells me a list of the highest ranking keywords which lead to a particular website's traffic in views and %. I've used Sumrush' Organic Research tool but understandably that only gives you a few results and none of them are the top results for the website I am rsearching. I understand why all these tools are paid but I'm only going to use the feature once so don't want to pay over $100. Any help or advice is greatly appreciated as I'm trying to smash this out! Thank you very much.