Top 5 open source Q&A systems

http://www.mkyong.com/featured/top-5-open-source-qa-systems/


List of the open source Q&A implementation or stackoverflow-like website, with “Active” development and promising features and community.

P.S This list is not in any particular order.
1. OSQA
osqa

    Website : http://www.osqa.net
    Demo : http://meta.osqa.net
    Language : Python, Django
    Database : MySQL, PostgreSQL or Microsoft SQL Server
    License : GNU General Public Licence (GPL)
    Source code : http://www.osqa.net/download/
    Created by : Folks at DZone

2. Shapado
shapado

    Website : http://shapado.com
    Demo : http://shapado.com
    Language : Ruby , MongoMapper
    Database : MongoDB (Document Based DB engine)
    License : GNU Affero General Public License (AGPL)
    Source code : http://gitorious.org/shapado
    Created by : David A. Cuadrado

3. Askbot
askbot

    Website : http://askbot.org
    Demo : http://askbot.org
    Language : Python, Django
    Database : MySQL, PostgreSQL
    License : GPL3
    Source code : https://github.com/ASKBOT/askbot-devel/
    Created by : Mike Chen and Sailing Cai

4. Question2Answer
question2answer

    Website : http://www.question2answer.org
    Demo : http://www.question2answer.org/qa/
    Language : PHP
    Database : MySQL
    License : GNU General Public Licence (GPL)
    Source code : http://www.question2answer.org/install.php
    Created by : Gideon Greenspan

5. LampCMS
lampcms

    Website : http://www.lampcms.com
    Demo : http://support.lampcms.com
    Language : PHP
    Database : MongoDB
    License : GNU LESSER GENERAL PUBLIC LICENSE (LGPL) version 3
    Source code : https://github.com/snytkine/LampCMS
    Created by : Dmitri Snytkine (Twitter)