[lee101]

Side note about rapid API, I originally built https://text-generator.io on rapid API but I got 0 customers there, you would think you could just look on rapid API to see the gaps, there wasn't and still isn't a good alternative to text-generator.io on there but that doesn't guarantee anything, market research takes a lot of thought and the product needs constant marketing just like all businesses, I had to launch it as its own website for it to get users, so there's a lot more that goes into it than just building the right API.

I've also had customers scared off or investors not want to invest because it is a plain API platform and not B2C...

To answer the question market research is kind of the only way to know, Google adwords keyword planner and Google trends are quite good, as well as researching the companies in the same space well and what gaps there APIs have.

As an example https://text-generator.io distinguishes itself from OpenAI by including automatic analysis for input links, linked images, documents etc and doing speech to text/self hosting/embedding images, text and code in the same space, so isn't just an API clone