HubSpot CRM - Free CRM software for small businesses.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Keap - Grow Sales. Save Time. Get Organized.
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.
Less Annoying CRM - A simple customer relationship manager made just for small businesses. Manage contact info, track leads, and never miss a follow-up.
Prometheus - An open-source systems monitoring and alerting toolkit.