Unshorten URLs with PHP and cURL

While working on a site that provides previews of URLs embedded in tweets using the awesome PhantomJS scriptable WebKit browser, and encountered difficulties when an URL shortener such as Bit.ly was used (as is almost always done when tweeting out a link to an interesting article or photo).

After a little experimenting, I discovered that cURL makes it super easy to un-shorten a URL that has been shortened, without depending on a thirdparty service.

Improving slightly on this function, here’s how I did it in PHP:

function unshorten_url($url) {
    $ch = curl_init($url);
    curl_setopt_array($ch, array(
        CURLOPT_FOLLOWLOCATION => TRUE,  // the magic sauce
        CURLOPT_SSL_VERIFYHOST => FALSE, // suppress certain SSL errors
    $url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
    return $url;

That’s all you have to do. This works even if multiple URL shorteners are used in sequence on the same link, and in the event of an error, you’ll just get the same link back that you started with.

This seems to be a bit more robust than some of the other solutions floating around the ‘net, since it doesn’t try to hack the response headers or body (which could change without notice), and it will recurse as many times as it needs to up to the value of the CURLOPT_MAXREDIRS setting.


Written on May 18, 2012