Proxy Workbench is a free MIT-licensed local tool for developers who need to know whether an HTTP(S), SOCKS4 or SOCKS5 proxy can reach their specific website or API. Collect public candidates or import your own list; define accepted status codes, expected text or a response hash; repeat checks and inspect each attempt. Rank and export passing results to TXT/CSV/JSON, PAC, proxychains, Clash/Mihomo or sing-box, or use the local rotating TCP gateway and API. Profiles, pools and schedules keep workflows repeatable. Windows/macOS builds, Linux CLI and headless Docker are available. No app account or telemetry. Public proxies are untrusted and measurements apply to their targets and time; the gateway is TCP-only. Submitted for the maintainer with AI assistance. Cover shows the real UI with synthetic demo results.