Examine source code of Kᴇplr

{
  "manifest_version": 2,
  "name": "Quick Text Stats",
  "version": "1.0.0",
  "description": "Count words and characters for the selection or the whole page (Supports English Language).",
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b5a87e37-4945-481b-a19d-699de2814c10}",
      "strict_min_version": "127.0"
    }
  },
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_action": {
    "default_title": "Quick Text Stats",
    "default_popup": "popup.html",
    "default_icon": {
      "64": "icon64.png",
      "128": "icon128.png"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}