The initial version of OOPSpam Anti-Spam API was a school project and I made it public to show my potential future employer. But people started to email me and show interest. So I improved it based on one customer who was willing to subscribe and he did.
.... but I was worrying that I won't able to go beyond my 1st customer. Even though I improve the product daily and redesigned the website, wrote blog posts.
So it was true that if you solve someone's problem, there are going to be someone else who also has the same problem.
Well, yesterday I got my 2nd customer who subscribed to ULTRA plan.
Hopefully, this trend will continue.