Fetching favicons

# Overview

A favicon (short for "favorite icon") is a small icon that is displayed in the browser's address bar. Favicons are typically used to identify and differentiate websites. This article describes how to retrieve a website’s favicon in a Manifest V3 extension.

# Accessing a website's favicon

To retrieve the favicon of a website, you need to construct the following URL:

chrome-extension://EXTENSION_ID/_favicon/?pageUrl=EXAMPLE_URL&size=FAV_SIZE

EXTENSION_ID

The ID of your extension.

EXAMPLE_URL

The URL of the favicon's website.

FAV_SIZE

The size of the favicon. The most common size is 16 x 16 pixels.

The following steps describe how to construct this URL in a Chrome extension:

# Step 1: update the manifest

First, you must request the "favicon" permission in the manifest.

{
  "name": "Favicon API in a popup",
  "manifest_version": 3,
  ...
  "permissions": ["favicon"],
  ...
}

In addition, when fetching favicons in content scripts, the "_favicon/*" folder must be declared as a web accessible resource. For example:

{
  "name": "Favicon API in content scripts",
  "manifest_version": 3,
  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["content.js"]
    }
  ],
  "permissions": ["favicon"],
  "web_accessible_resources": [
    {
      "resources": ["_favicon/*"],
      "matches": ["<all_urls>"],
      "extension_ids": ["*"]
    }
  ]
  ...
}

# Step 2: construct the URL

The following function uses runtime.getURL() to create a fully-qualified URL pointing to the "_favicon/" folder. Then it returns a new string representing the URL with several query parameters. Finally, the extension appends the image to the body.

function faviconURL(u) {
  const url = new URL(chrome.runtime.getURL("/_favicon/"));
  url.searchParams.set("pageUrl", u);
  url.searchParams.set("size", "32");
  return url.toString();
}

const img = document.createElement('img');
img.src = faviconURL("https://www.google.com") 
document.body.appendChild(img);

This example is a www.google.com 32px favicon URL that includes a random extension ID:

chrome-extension://eghkbfdcoeikaepkldhfgphlaiojonpc/_favicon/?pageUrl=https%3A%2F%2Fwww.google.com&size=32

# Extension examples

There are two favicon examples in the chrome-extension-samples repository:

• Favicon popup example.
• Favicon content script example.