I have created a novel and very useful website. Now it is undergoing internal testing. It is a time trading platform. You spend your time doing something(can be anything) for others and get paid. Now the problem I am not clear what my core competency is. I figured out the idea and developed the website and of course I know how to use it and in what direction to improve it all along, but I have no idea what my core competency is. If an investor asks me, "What is your core competency?" How can I answer?
Your core competency is what your company does well, not what the application does.
So, if your application was marketed as a way to help people to tutor other people, and later you decide to market it in a different way, then that doesn't change your core competencies.
But, you will want to focus your approach on some segment, rather than telling people that it can be used for anything.
If you focus the marketing then you can help guide people to understand what you are doing, what they are investing in, and later, as you gain users, then you can start to expand it out to other areas.
So, what is your basic business? Perhaps writing web applications.
What is your area of greatest expertise? Perhaps ASP.NET?
But, you may also have something that is a great expertise that doesn't deal with software, that can be beneficial, so that could be included.
Notice that this has nothing to do with what your product does.
James' answer is very accurate; a core competency is what you do well. The core competency of your company is what your company does well
If what you're wondering is, "How do I decide what a fairly new one-person company does well?" (understandable) you may find it useful to reframe the question as:
"What is it that is going to make my company succeed over its competitors (such as Mechanical Turk and similar microservice platforms)?"
Is it your design philosophy? Your technical competence? Your choice of feature set? Will low barriers to entry make it feasible for a wider audience to use? Etc., etc.
It's a trick question, and a useless one at that. What an investor wants to know is what is it about what you are doing that is going to stand some small but non-zero chance of me making 20,30, 100X my investment. Any single "competency" can be beat by someone else.
Instead its about the entire package you are offering as value - the web site, what it does and how it does it, your company's attitude, values, vision, the community you build.
If you have to have an answer to this question, I'd say its "building an efficient and profitable market for trading work between internet savvy users"