本番サイトでアラート (Alerts on Live Sites) is a free Chrome add-on developed by ynobuo72. As the name suggests, this add-on displays alerts on the screen when accessing live sites.

With this add-on, users can register specific domains in the options settings. When accessing any of these registered domains, a pop-up alert will appear on the screen with the message "本番です！！" (which translates to "It's live!!" in English). This feature can be useful for developers or website administrators who want a visual reminder that they are accessing a live site.

By providing a simple and straightforward way to display alerts on live sites, 本番サイトでアラート offers a convenient tool for those who work with web development or website management. It is easy to use and can help prevent accidental changes or updates on live sites.

Please note that this add-on is only available for the Chrome browser and falls under the category of Browsers, specifically Add-ons & Tools.