How do proxy checkers work?

[Jack]

 I’ve heard people talk about proxy checkers to validate IP addresses, but I’m not entirely sure how they work or what to look for. Could anyone explain what these tools do and how reliable they are for security checks?

[Simon55]

Proxy checkers help users verify if a proxy is active and detect its anonymity level. Using a reliable proxy checker online proxy-checker.net/en/ can ensure your proxies are functioning properly and safe to use.