Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
Dr. Link Check - Broken link checker with malware and parked domain detection
AppDynamics - Get real-time insight from your apps using Application Performance Management—how they’re being used, how they’re performing, where they need help.
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks
Zabbix - Track, record, alert and visualize performance and availability of IT resources
LinkChecker - LinkChecker is a free, GPL licensed website validator.