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.
ReadTheDocs - Spend your time on writing high quality documentation, not on the tools to make your documentation work.
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.
HackMD - Fast and flexible, real-time collaborative markdown, inspired by Hackpad.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Documize - Enterprise-grade wiki and knowledge management platform