Examine source code of REST Tester

{
  "manifest_version": 2,
  "name": "REST Tester",
  "version": "1.0.0",
  "description": "Test popular public APIs with one click or send custom GET/POST/PUT/DELETE requests. See status, time, and JSON response.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{794b125e-29e4-4903-bd6c-e0f5f72e6118}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "assets/icons/icon16.png",
      "32": "assets/icons/icon32.png",
      "48": "assets/icons/icon48.png",
      "96": "assets/icons/icon96.png",
      "128": "assets/icons/icon128.png"
    },
    "default_title": "REST Tester",
    "default_popup": "src/popup.html"
  },
  "icons": {
    "16": "assets/icons/icon16.png",
    "32": "assets/icons/icon32.png",
    "48": "assets/icons/icon48.png",
    "96": "assets/icons/icon96.png",
    "128": "assets/icons/icon128.png"
  }
}