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

2. Shapado

shapado

3. Askbot

askbot

4. Question2Answer

question2answer

5. LampCMS

lampcms
Best Engine ?
Personally, i will go for OSQA, for their huge community in DZone.

References

  1. MongoDB
  2. MongoMapper
  3. Django Web Framework
  4. GNU GPL license
  5. Stack Overflow clones