manifest.json

{
  "name": "Duolingo Plus",
  "version": "1.0",
  "description": "Immerse yourself in a different language by changing the language of any (and all) websites you visit to a random language.\nN.B. All http and https websites are supported except for the following search engines: Google, Bing, DuckDuckGo, Yahoo!, Baidu, and Yandex",
  "manifest_version": 2,
  "permissions": ["*://*/*"],
  "content_scripts": [
    {
      "matches": ["*://*/*"], 
      "js": ["languages.js", "main.js"], 
      "exclude_matches": [
        "https://www.google.com/*", 
        "https://www.bing.com/*",
        "https://duckduckgo.com/*",
        "https://ca.search.yahoo.com/*",
        "https://www.baidu.com/*",
        "https://yandex.ru/*"
    ]
    }
  ],
  "browser_action": {
    "default_icon": "icon.png"
  },
  "icons": {
    "128": "icon.png"
  }
}