Nibbler

manifest.json

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "Nibbler",
  "description": "Test your website",
  "version": "1.0",
  "browser_action": {
    "icons": {
      "32": "Nibbler.png",
      "128": "icon128.png"
    },
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ]
}