It's a little like SSLlabs server test, only much faster (5 seconds instead of 2 minutes), plus the tests are recurring every day, and you receive the diff if any.
It's always been a joy to receive thank you emails from users, or adding new features for users.
SSLping also allowed me to learn React and Redux. I'm still working on it, adding new features and refactoring what I don't like.
If I ever have to stop hosting it, I'll open source the whole thing. Or maybe I'll open source it anyway. If I could find a deal with a security company, I would work on it fulltime.
I consider it's a success, even if the numbers are not as high as I'd like.