Are any of your apps public? I want to try using them.
I find that once a company uses the product, they never stop. The customer base is very sticky.
I have also found that I bounce a lot of companies that don't "get it". They don't understand that it's about making things better for candidates and so all they see is Hackerrank with less features.
My challenge for growth is finding better ways to explain the ethos and the benefits to those companies.