Kinda underwhelming considering it only checks four services and gives priority to random TLDs. But the idea itself has always been useful when doing naming/branding work.
Checking if a username is available is pretty hard on some sites. Instagram, for example doesn't allow me to check profiles without logging in, doesn't allow to me to try and create an account to check for user error, and has most proxies banned from their server.
This was moreso an idea that I wanted to put together a quick prototype for! Thanks for taking the time.