For a better understanding of the progress of the proxies checks, here is an example of code using an flexible ascii progress bar: node-progress.

Rem: Pool is not accessible via require('free-proxy-checker')

// https://github.com/antoinevastel/free_proxy_checker
const { ProxyChecker, downloadAllProxies, } = require('free-proxy-checker');
// https://github.com/visionmedia/node-progress
const ProgressBar = require('progress');

const { Pool } = require('./pool.js');

class ProgressProxyChecker extends ProxyChecker {
    async checkProxies() {
        this.lastCheck = Date.now();
        const pool = new Pool(this.options.concurrency);
        const pbar = new ProgressBar('Checking proxies [:bar] :percent :etas', {
            complete: '=',
            incomplete: ' ',
            width: 20,
            total: this.proxies.length
        });

        this.proxies.forEach((proxy) => {
            pool.addTask(async() => {
                try {
                    await proxy._testConnection(this.options.timeout);
                } catch (_) { }
                finally {
                    if (this.options.verbose) {
                        pbar.tick();
                    }
                }
            })
        })

        await pool.run();
    }
}

(async () => {
    // Clear console
    process.stdout.write('\033c');

    // Download all proxies from all proxy providers at once
    const allProxies = await downloadAllProxies();
    console.log(`There are ${allProxies.length} proxies to test`);

    // Check the availability of the proxies we downloaded
    const proxyChecker = new ProgressProxyChecker(allProxies, {
        concurrency: 50,
        timeout: 7500,
        verbose: true
    })

    await proxyChecker.checkProxies();
    const proxiesUp = proxyChecker.getProxiesUp();
    console.log(`There are ${proxiesUp.length} proxies UP:`);
})();

Result:

Add 2 new proxy providers:

• geonode
• spys me

Fix bug when deduplicating proxies while calling downloadAllProxies. I was leveraging Set of objects in JS. However, there were still duplicates since objects were considered unique as they didn't have the same reference (even though they had the same values)

Improve verification before creating proxies. Check if host is a proper IP.

I think it would be more interesting to use a Proxy Judge like azenv.php to test the proxies (see: http://azenv.net/, http://httpheader.net/azenv.php).

Moreover with a Proxy Judge we can know what is

• the type of anonymity of the proxy.
• the response time of the proxy.

It would be interesting to resolve IPs proxies to country codes/names. To do this, we can use a free service such as

• ip2c.org.
• ip-api. Their API Batch processing is interesting. My preference.
• ipgeo.
• ipwhois. API is free for up to 10,000 requests per month.

Example ip2c: https://ip2c.org/1.0.205.8 Result: 1;TH;THA;Thailand

Example ipwhois: https://ipwhois.app/json/1.0.205.8 Result:

{
  "ip": "1.0.205.8",
  "success": true,
  "type": "IPv4",
  "continent": "Asia",
  "continent_code": "AS",
  "country": "Thailand",
  "country_code": "TH",
  "country_flag": "https://cdn.ipwhois.io/flags/th.svg",
  "country_capital": "Bangkok",
  "country_phone": "+66",
  "country_neighbours": "LA,MM,KH,MY",
  "region": "Phuket",
  "city": "Thalang District",
  "latitude": 8.0320027,
  "longitude": 98.3334626,
  "asn": "AS23969",
  "org": "TOT Public Company Limited",
  "isp": "TOT Public Company Limited",
  "timezone": "Asia/Bangkok",
  "timezone_name": "Indochina Time",
  "timezone_dstOffset": 0,
  "timezone_gmtOffset": 25200,
  "timezone_gmt": "GMT +7:00",
  "currency": "Thai Baht",
  "currency_code": "THB",
  "currency_symbol": "฿",
  "currency_rates": 33.562,
  "currency_plural": "Thai baht",
  "completed_requests": 2
}