i use a whole suite of stuff to monitor uptime/status.
upptime is the public facing tool i use for websites/public services.
zabbix monitors web services from within my lab.
uptimerobot is still in use too, though i do plan on phasing it out in the coming months.

for alerts:
gotify - is my primary tool for sending notifications.
upptime and zabbix both send alerts to my mattermost instance, located at