website broken link and 404 error checker

{
    "update_url": "https:\/\/clients2.google.com\/service\/update2\/crx",
    "manifest_version": 3,
    "version": "1.1.1",
    "name": "__MSG_appName__",
    "description": "__MSG_appDesc__",
    "default_locale": "en",
    "permissions": [
        "tabs"
    ],
    "host_permissions": [],
    "icons": {
        "128": "icon\/icon128.png"
    },
    "content_scripts": [
        {
            "matches": [
                "<all_urls>"
            ],
            "js": [
                "js\/chunk-vendors.js",
                "js\/content.js"
            ],
            "css": [
                "css\/main.css"
            ],
            "run_at": "document_start"
        }
    ],
    "background": {
        "service_worker": "js\/background.js",
        "type": "module"
    },
    "action": {
        "default_icon": "icon\/icon128.png",
        "default_title": "popup",
        "default_popup": "popup.html"
    },
    "web_accessible_resources": [
        {
            "resources": [
                "img\/*",
                "icon\/*"
            ],
            "matches": [
                "<all_urls>"
            ]
        }
    ],
    "content_security_policy": {
        "extension_pages": "script-src 'self'; object-src 'self'; frame-src 'self'; child-src 'self'"
    }
}