Is it possible to use Colly with a proxy?

Yes, it is possible to use Colly, the popular Go library for web scraping, with a proxy. Colly has built-in support for HTTP/HTTPS proxies which you can set up for your collector.

In order to use a proxy with Colly, you will need to configure the Collector's ProxyFunc. Here is an example of how to set a proxy using Colly:

package main

import (
    "fmt"
    "log"

    "github.com/gocolly/colly"
    "github.com/gocolly/colly/proxy"
)

func main() {
    // Create a new collector
    c := colly.NewCollector()

    // Set up a proxy
    if err := c.SetProxy("http://your-proxy-address:port"); err != nil {
        log.Fatal(err)
    }

    // Alternatively, you can use the proxy switcher for a list of proxies:
    // rp, err := proxy.RoundRobinProxySwitcher("http://proxy1.com", "http://proxy2.com")
    // if err != nil {
    //  log.Fatal(err)
    // }
    // c.SetProxyFunc(rp)

    // On every a element which has href attribute call callback
    c.OnHTML("a[href]", func(e *colly.HTMLElement) {
        link := e.Attr("href")
        fmt.Printf("Link found: %q -> %s\n", e.Text, link)
    })

    // Start scraping on http://example.com
    c.Visit("http://example.com")
}

In this example, you need to replace "http://your-proxy-address:port" with the actual address and port of the proxy you want to use. If you have multiple proxies and would like to rotate between them, you can use the RoundRobinProxySwitcher, which allows you to pass in a list of proxy addresses.

Please note that if you are using proxies that require authentication, you might need to include the credentials in the proxy URL, like so:

c.SetProxy("http://username:password@your-proxy-address:port")

Keep in mind that using proxies can sometimes be against the terms of service of the website you are scraping, and your activities may be subject to legal and ethical considerations. Always be respectful of the websites you scrape, adhere to their robots.txt policies, and don't overload their servers with too many requests in a short period of time.