Stack Exchange

Stack Exchange is a fast-growing network of 84 [and counting] question and answer sites on diverse topics from software programming to cooking to photography and gaming.

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Super User

super user, part of stack exchange , is a q&a site for computer enthusiasts that's free.

Free Web

Server Fault

Server Fault is a Q&A site for system administrators and IT professionals that's free.

Free Web

Question2Answer

A Q&A site helps an online community to share knowledge. No matter what your area of interest, people with questions can get super answers fast. Question2Answer is a popular Q&A solution.

Free Open Source Mac OS X Windows Linux Web Self-Hosted PHP MySQL Community Edition

OSQA

OSQA is the free, open source Q&A system you've been waiting for. Your OSQA site is more than just an FAQ page, it is a full-featured Q&A community.

Free Open Source Web Self-Hosted Django Python

Solace

Solace is a fully open-sourced multilingual support and knowledge exchange platform written in Python.

Free Open Source Mac OS X Windows Linux Web

Coordino

Coordino allows you to create a question and answer system for you and your users to enjoy.

Free Open Source Linux Web Self-Hosted

Experts Exchange

The Mission Our patented knowledge-sharing process, combined with the advantages of the Internet, allow us to change the way people solve their technology problems...

Commercial Web

Askalot

Askalot is a next generation CQA (Community Question and Answer) system.

Free Open Source Self-Hosted