The Domain Health Check is a small component of the CyberDrain Improved Partner Portal. This is designed to be run as a public facing Static Web App providing visibilty into common problems with domains.
If you are a Microsoft Partner interested in better management of your tenant environments, check us out here.
If you want to self-host, you will need some knowledge of Static Web Apps.
It is highly recommended to proxy this SWA through a service like CloudFlare to prevent abuse.