Stack Overflow is the largest online community for programmers to learn, share their knowledge, and advance their careers.

Stack Exchange is a network of question-and-answer websites on topics in varied fields.

Glisser is an online platform that allows you to create interactive presentations that can be used for marketing, training.

Slant Community’s guides to all the best stuff.

Server Fault is a community QnA site about servers.

Question2Answer is a free and open source platform for Q&A sites.

AskBot is a Django/Python Q&A forum.

OSQA (Open Source Question and Answer) is an open source question-answer system written in PythonLearn More with Django.

Reddit is an social news aggregation, web content rating, and discussion website.

Quora is a question-and-answer site where questions are asked, answered, edited and organized by its community of users.

Super User is a Q&A sites for system admins.

Niftio is a presentation app that offers its users all the necessary resources they need to become the presenters they secretly crave to be.

Pubble provides real-time messaging to drive customer engagement.

Wooclap is a collaborative platform for your conferences and your training sessions.

Yahoo! Answers is a community-driven question-and-answer (Q&A) website.