Examine source code of CashBackStacks

{
  "manifest_version": 3,
  "name": "CashBackStacks: Stack & Maximize Rewards",
  "description": "Automatically stack cashback from portals, credit cards, card-linked offers, and gift cards. Never leave money on the table.",
  "version": "1.1.1",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "48": "icons/48.png",
    "128": "icons/128.png"
  },
  "author": "CashBackStacks",
  "homepage_url": "https://cashbackstacks.com",
  "permissions": [
    "activeTab",
    "scripting",
    "storage",
    "alarms",
    "cookies",
    "declarativeNetRequestWithHostAccess"
  ],
  "optional_permissions": [
    "notifications"
  ],
  "host_permissions": [
    "https://www.amazon.com/*",
    "https://www.amazon.ca/*",
    "https://www.amazon.com.mx/*",
    "https://www.amazon.com.br/*",
    "https://www.amazon.co.uk/*",
    "https://www.amazon.de/*",
    "https://www.amazon.fr/*",
    "https://www.amazon.it/*",
    "https://www.amazon.es/*",
    "https://www.amazon.nl/*",
    "https://www.amazon.in/*",
    "https://www.amazon.co.jp/*",
    "https://www.amazon.com.au/*",
    "https://*.cashbackstacks.pages.dev/*",
    "https://cashbackstacks.com/*",
    "https://www.cashbackstacks.com/*",
    "https://cdn.cashbackstacks.com/*",
    "https://capitaloneshopping.com/*",
    "https://www.capitaloneshopping.com/*",
    "https://www.paypal.com/*",
    "https://clerk.cashbackstacks.com/*",
    "https://improved-boa-70.clerk.accounts.dev/*"
  ],
  "optional_host_permissions": [
    "https://capitaloneoffers.com/*",
    "https://www.capitaloneoffers.com/*",
    "https://*.americanexpress.com/*",
    "https://*.chase.com/*",
    "https://*.citi.com/*",
    "https://*.usbank.com/*",
    "https://www.simplymiles.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "extension@cashbackstacks.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "CashBackStacks",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/cashbackstacks.js"
      ]
    },
    {
      "matches": [
        "https://duckduckgo.com/*",
        "https://search.yahoo.com/search*",
        "https://www.bing.com/search*",
        "https://www.ecosia.org/search*",
        "https://www.google.ca/search*",
        "https://www.google.co.in/search*",
        "https://www.google.co.jp/search*",
        "https://www.google.co.kr/search*",
        "https://www.google.co.nz/search*",
        "https://www.google.co.uk/search*",
        "https://www.google.co.za/search*",
        "https://www.google.com.au/search*",
        "https://www.google.com.br/search*",
        "https://www.google.com.hk/search*",
        "https://www.google.com.mx/search*",
        "https://www.google.com.sg/search*",
        "https://www.google.com/search*",
        "https://www.google.de/search*",
        "https://www.google.es/search*",
        "https://www.google.fr/search*",
        "https://www.google.it/search*",
        "https://www.google.nl/search*",
        "https://www.google.pl/search*",
        "https://www.google.ru/search*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/search-badges.js"
      ]
    },
    {
      "matches": [
        "https://capitaloneoffers.com/*",
        "https://capitaloneshopping.com/*",
        "https://global.americanexpress.com/offers*",
        "https://online.citi.com/*",
        "https://onlinebanking.usbank.com/*",
        "https://secure.chase.com/*",
        "https://www.capitaloneshopping.com/*",
        "https://www.paypal.com/offers/*",
        "https://www.simplymiles.com/*"
      ],
      "run_at": "document_idle",
      "js": [
        "content-scripts/sync-widget.js"
      ]
    },
    {
      "matches": [
        "https://cashbackstacks.com/*",
        "https://www.cashbackstacks.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/website-bridge.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "content-scripts/cashbackstacks.css"
      ],
      "use_dynamic_url": true,
      "matches": [
        "https://*/*"
      ]
    },
    {
      "resources": [
        "content-scripts/sync-widget.css"
      ],
      "use_dynamic_url": true,
      "matches": [
        "https://capitaloneoffers.com/*",
        "https://capitaloneshopping.com/*",
        "https://global.americanexpress.com/*",
        "https://online.citi.com/*",
        "https://onlinebanking.usbank.com/*",
        "https://secure.chase.com/*",
        "https://www.capitaloneshopping.com/*",
        "https://www.paypal.com/*",
        "https://www.simplymiles.com/*"
      ]
    }
  ]
}