Hi, I've just visited the only free potential activity checker I know which is visitorsbit.com but it seems the site was gone coz I redirected to hostinger site error page. I just wanna ask if there's a similar site and is FREE. Kindly reply here if you know one. Thanks!

For more links check Potential Activity Checker Service?.
If you don't want to wait in queue, you could always install XAMPP on your localhost and run it by yourself.