Examine source code of FPL Tools

{
  "description": "Tools to help fantasy premier league manager",
  "version": "5.1.0",
  "name": "FPL Tools",
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "64": "icon-64.png",
    "128": "icon-128.png"
  },
  "action": {
    "default_icon": "icon-32.png",
    "default_popup": "options.html"
  },
  "permissions": [
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.fantasy.premierleague.com/*",
        "*://*.draft.premierleague.com/*"
      ],
      "js": [
        "fpl.js"
      ],
      "css": [
        "fpl.css"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "index.js"
      ],
      "matches": [
        "*://*.fantasy.premierleague.com/*",
        "*://*.draft.premierleague.com/*"
      ]
    }
  ],
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'self'"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "fpl-tools@amitchauhan"
    }
  },
  "manifest_version": 3
}