Ask HN: How do you research if a startup idea already exists?

Hey there,

As, I assume a lot of people do, I have this endless Google Keep list of startup ideas that keeps getting longer and longer.

However, I'm a novice when it comes to finding the right terms to search if that idea already exists. I simply Google around with whatever feel relevant only to realise, months later, that there is a much better field-specific term or some vague jargon/synonym of what I was supposed to be searching for.

I assume this should be a somewhat elementary issue to vet startups and do competitor analysis.

How do you do that?

Also, what measures do you use to figure out the strength of the competing solutions?