Friend... I tested this service and it works good for known proxy servers and TOR IPs.
However it is not good to new proxy severs and bad IPs. I think this service is not checking scam and bot address too...
GetIpIntel is working better.
Anyways... I just developed a very effective proxy server barrier!
My solution has 4 layers of protection.
1st layer: Custom IPs blacklist and cache. Supported by the layers above and customizable if your personal IPs blacklist.
2nd layer: TOR users protection. Almost 100% effective.
3rd layer: Popular and Known Proxy Servers blocked.
4th layer: Unknown proxies blocked by intelligent algorithms.
It works for any site running PHP.
If you are interested in a deal, send me a PM. You can test the service first.