Slack Overflow - A programmer's best friend, now in Slack.
Dr.Explain - Dr.Explain software is a help file authoring tool.
GitCommands - An interactive reference tool for Git commands
MadCap Flare - Documentation for Any Audience, Language or Format
GitHub + Slack Integration - Full visibility into your GitHub projects right inside Slack
HelpNDoc - What is HelpNDoc ? Easy to use yet powerful help authoring environment which can generate various documentation formats from a single source.