Examine source code of Icon Finder

{
  "name": "__MSG_app_name__",
  "description": "__MSG_app_description__",
  "default_locale": "en",
  "version": "1.0.3",
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "icon-finder@cool-cursors.com",
      "strict_min_version": "42.0"
    }
  },
  "icons": {
    "16": "img/icon.png",
    "48": "img/icon_128.png",
    "128": "img/icon_128.png"
  },
  "homepage_url": "https://icon-finder.freebusinessapps.net",
  "browser_action": {
    "default_icon": "img/icon.png",
    "default_popup": "popup.html"
  },
  "background": {
    "scripts": [
      "js/background.js"
    ]
  },
  "permissions": [
    "https://*.freebusinessapps.net/*"
  ]
}