Examine source code of Numberle

{
  "manifest_version": 2,
  "name": "Numberle",
  "version": "1.0",
  "description": "Play Numberle Wordle game | A daily number game",
  "icons": {
    "48": "icons/48.png",
    "128": "icons/128.png",
    "256": "icons/48.png",
    "512": "icons/48.png"
  },
  "browser_action": {
    "default_icon": "icons/48.png",
    "default_title": "Numberle",
    "default_popup": "index.html"
  },
  "applications": {
    "gecko": {
      "strict_min_version": "58.0",
      "id": "numberlewordle-firefox@robwu.nl"
    }
  }
}