Practical guidance
Identify the protocol: HTTP proxies, HTTPS CONNECT and SOCKS work differently. An open port does not guarantee access to a resource. Account for authentication, DNS handling and outbound traffic restrictions.
Before using this tool
Define what you need from Proxy checker and prepare the relevant input. When diagnosing a live service, record the test time and connection conditions so you can compare results after configuration changes. Check findings against the documentation for your software.
Tool availability
This is currently an information page. No working form, calculations or submission to diagnostic services is available yet. The interface and supported input formats will be documented when functionality is released.