Google Ads is one of the most powerful sources of market data in the world. It used to be called AdWords and completely free just by . These days you have to provide a credit card and pre-pay $50 that Google returns after a few days. So it’s still free, but you have to be willing to go through the (slight) hassle of providing a credit card. It’s 100% worth it.
Once you have a Google Ads account, you insert search phrases related to your idea into the keyword planning tool, and it’ll reveal powerful data. For example, in the chart below, I’ve entered a small constellation of search terms related to rock climbing.
The keyword planning tool shows me the number of impressions (i.e., searches) on those terms each day and the estimated number of paid clicks I could get with a given budget.