I’m assuming you want to monitor if an HTTP endpoint is alive and responding with a 200, maybe at a particular URL?
You can use the Services Nagios Plugins to do this - there is some setup to do in LibreNMS, and the rest of it is specific to the actual nagios plugin you use: Nagios Plugins - LibreNMS Docs
You can then use the http check (check_http) to set a status based on the response, for example if you want to monitor http://1.1.1.1/help - you can do this:
You assign that service to a host - for example a ping-only host of the same IP, and can assign that service to it, and get these results on a Services tab on the host:
