Examine source code of Header Forge

{
  "manifest_version" : 3 ,
  "name" : "Header Forge",
  "version" : "1.0.0",
  "description" : "Modify HTTP request and response headers. Add, override, or remove headers with per-rule toggles and URL filters.",
  "permissions" : [
    "declarativeNetRequest" ,
    "storage" 
  ],
  "host_permissions" : [
    "<all_urls>" 
  ],
  "background" : {
    "scripts" : [
      "background.js" 
    ]
  },
  "action" : {
    "default_popup" : "popup.html",
    "default_icon" : {
      "16" : "icons/icon16.png",
      "48" : "icons/icon48.png",
      "128" : "icons/icon128.png"
    }
  },
  "icons" : {
    "16" : "icons/icon16.png",
    "48" : "icons/icon48.png",
    "128" : "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "header-forge@example.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}