Examine source code of REST API testing client

{
  "manifest_version": 2,
  "name": "RESTClient",
  "version": "1.0",
  "description": "A simple REST API testing client.",
  "permissions": [
    "<all_urls>"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "RESTClient"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{12ff8508-6814-4aac-9236-e90eccc85b8d}"
    }
  }
}