FineProxyを利用環境に接続。

curl -x http://USER:PASS@HOST:PORT http://api.ipify.org

import axios from "axios";
import { HttpProxyAgent } from "http-proxy-agent";
import { HttpsProxyAgent } from "https-proxy-agent";

const proxyUrl = "http://USER:PASS@HOST:PORT";
const res = await axios.get("https://api.ipify.org", {
  httpAgent: new HttpProxyAgent(proxyUrl),
  httpsAgent: new HttpsProxyAgent(proxyUrl),
  timeout: 20000,
});
console.log(res.data);

import requests
proxies = {
    "http": "http://USER:PASS@HOST:PORT",
    "https": "http://USER:PASS@HOST:PORT"
}
print(requests.get("https://api.ipify.org", proxies=proxies, timeout=20).text)

<?php
$proxy = "http://USER:PASS@HOST:PORT";
$ch = curl_init("https://api.ipify.org");
curl_setopt($ch, CURLOPT_PROXY, $proxy);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 20);
echo curl_exec($ch);
curl_close($ch);

proxyURL, _ := url.Parse("http://USER:PASS@HOST:PORT")
client := &http.Client{
  Timeout: 20 * time.Second,
  Transport: &http.Transport{Proxy: http.ProxyURL(proxyURL)},
}
resp, err := client.Get("https://api.ipify.org")