I worked at Google for 4 years. One thing that has always surprised me about documentation at Google is that they use Google Docs (just like everyone else) but have never seemed interested in making it less of a terrible tool for the task. It's relentlessly print oriented, which makes almost no sense these days (when was the last time you printed out a Google doc?), has no affordances for dealing with pre-formatted t…
At my workplace, we've started using Confluence for some projects and it's been incredibly productive. I still loathe JIRA but Confluence has been incredibly good for technical collaboration and documentation.
Confluence is brillient, bitbucket is meh but OK and JIRA is an utter tire fire both in how it's built and what it does but PHB's and PHB-shaped objects love it.