Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
Askalot - Askalot is a next generation CQA (Community Question and Answer) system.
wikiHow - wikiHow is a wiki based collaboration to build the world’s largest, highest quality how to manual.
Blurtit - Blurtit is a Q&A website. You can ask a question or answer on any question.
Scoold - An open-source, enterprise-friendly Q&A platform inspired by Stack Overflow.