You've built a web prototype of a product, which means you had some idea of what the product should do, and what business problem it should solve, and who it should be useful to.
Presumably, in doing that, you relied on the input of some target customers to help you understand their business. Right? (If not, well, then we need to have a different conversation.)
My point is: you should already have personal contacts who are also prospects. And those folks should each have a rolodex full of further prospects.
So, if it were me, I'd call someone I knew (i.e, not cold-call) and ask for a face-to-face. I'd offer them a free trial, in exchange for feedback after they've used the product for a while. If the feedback is positive, ask for leads.
Rinse, lather, repeat, and you should have a decent test for your MVP.