How can I get a web site's favicon?

Question

You'll want to tackle this a few ways:

1. Look for the favicon.ico at the root of the domain

   www.domain.com/favicon.ico

2. Look for a <link> tag with the rel="shortcut icon" attribute

   <link rel="shortcut icon" href="/favicon.ico" />

3. Look for a <link> tag with the rel="icon" attribute

   <link rel="icon" href="/favicon.png" />

The latter two will usually yield a higher quality image.

---

Just to cover all of the bases, there are device specific icon files that might yield higher quality images since these devices usually have larger icons on the device than a browser would need:

<link rel="apple-touch-icon" href="images/touch.png" />

<link rel="apple-touch-icon-precomposed" href="images/touch.png" />

---

And to download the icon without caring what the icon is you can use a utility like http://www.google.com/s2/favicons which will do all of the heavy lifting:

var client = new System.Net.WebClient();

client.DownloadFile(
    @"http://www.google.com/s2/favicons?domain=stackoverflow.com",
    "stackoverflow.com.ico");

Updated 2020

Here are three services you can use in 2020 onwards

<img height="16" width="16" src='https://icons.duckduckgo.com/ip3/www.google.com.ico' />

<img height="16" width="16" src='http://www.google.com/s2/favicons?domain=www.google.com' />

<img height="16" width="16" src='https://api.statvoo.com/favicon/?url=google.com' />

You can use Google S2 Converter.

http://www.google.com/s2/favicons?domain=google.com

Source: http://www.labnol.org/internet/get-favicon-image-of-websites-with-google/4404/

It's a good practice to minimize the number of requests each page needs. So if you need several icons, yandex can do a sprite of favicons in one query. Here is an example http://favicon.yandex.net/favicon/google.com/stackoverflow.com/yandex.net/

The first thing to look for is /favicon.ico in the site root; something like WebClient.DownloadFile() should do fine. However, you can also set the icon in metadata - for SO this is:

<link rel="shortcut icon"
   href="http://sstatic.net/stackoverflow/img/favicon.ico">

and note that alternative icons might be available; the "touch" one tends to be bigger and higher res, for example:

<link rel="apple-touch-icon"
   href="http://sstatic.net/stackoverflow/img/apple-touch-icon.png">

so you would parse that in either the HTML Agility Pack or XmlDocument (if xhtml) and use WebClient.DownloadFile()

Here's some code I've used to obtain this via the agility pack:

var favicon = "/favicon.ico";
var el=root.SelectSingleNode("/html/head/link[@rel='shortcut icon' and @href]");
if (el != null) favicon = el.Attributes["href"].Value;

Note the icon is theirs, not yours.