What method do you usually use to find the app you want?

Hello. It's ambiguous to be a programming-related Q/A, but I registered for the question because I was so curious.

Usually, when you want to develop an application, you need to create ideas first to create goals and proceed with development. I don't think we're going to develop goals simply by subjective thinking, "This is going to be useful.

Perhaps because the above idea was at the bottom, I searched on the Internet and looked it up, but there was no suitable experience or advice. How do other current developers or single-person developers usually look for materials?

There are people who make it because they need it, and there are people who start it simple and gradually increase it. And is there a site that collects data about the application you want or the trend of applications these days?

I would really appreciate it if you could tell me in detail.