What is proxy-checker?

Proxy Checker is a web-based tool for testing lists of free proxy servers to find ones that actually work. A proxy is a middleman server that routes your internet traffic, and free proxies are often unreliable, so this tool automates the process of checking a large number of them quickly. The README is written in Chinese, but the tool is general-purpose and the interface is web-based. The tool fetches proxy lists from several public free-proxy sources automatically and then tests each one in parallel, up to 30 at a time by default. For each proxy it checks basic connectivity and identifies the exit IP address, country, and whether the IP appears to be a data-center or residential address. Beyond generic connectivity, there are five testing modes: a general HTTPS check, and four service-specific checks that verify whether the proxy can reach OpenAI and the ChatGPT API, Grok, Google Gemini, or Claude and the Anthropic API. This makes it useful for people who need proxies that can pass AI service restrictions. Working proxies get saved to a local storage area called a repository. The repository is tagged with metadata such as which AI services the proxy can reach, whether it bypasses Cloudflare, IP type, and country. The repository generates a stable public URL so other programs can pull the current list of working proxies in plain text. Each time the checker runs, previously checked proxies are skipped by default unless you force a recheck. The backend is a Python HTTP server. The frontend is a plain HTML page with a JavaScript file. No framework is required. Starting it takes three commands: clone the repo, install Python dependencies, and run the server. It runs on port 8888 by default and is protected by a password (the default is linux.do, which the README advises you to change before deploying). Configuration can be set through a local config file or environment variables. The README notes that proxy test results depend on where the checker is deployed: a proxy that works from one server may not work from yours, so the tool is most accurate when deployed on the same machine that will actually use the proxies.