Whenever I downloaded fresh proxy lists I always wondered how many entries were actually usable because appearances can be very misleading. I didn't like relying on guesswork, so I searched Google for a dependable verification tool and eventually found proxy server checker https://proxy-checker.net/en/. Since then I always check new proxies before putting them into use, which has saved me a lot of unnecessary troubleshooting. I feel much more confident because I know which proxies are worth keeping. The process is quick enough that I never skip it anymore. It has become an essential part of my workflow.