Friends, I recently came across information on the Internet that there are effective tools for checking whether the server is working properly. Can you suggest this resource?

Yes, in order to ensure stable and uninterrupted access to the network, it is important to check the proper functioning of proxy servers. Sometimes it's to ensure that you can work freely without delays, and sometimes it's just for relaxation. As for the tool for checking, you've probably read about the free Proxy Checker. You can use it to check your proxy servers, their speed, and how secure they are https://floppydata.com/free-proxy-checker/