Question2Answer!

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. We are an expert knowledge exchange: a place where physics researchers can ask each other about quantum entanglement, computer programmers can ask about JavaScript date formats, and photographers can share knowledge about taking great pictures in the snow.

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. Users earn points and badges for useful participation, and everyone in the community wins.

Askbot is a Q&A system, like StackOverflow, Yahoo Answers and some others. Askbot is based on code of CNPROG, originally created by Mike Chen and Sailing Cai and some code written for OSQA.

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

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

Shapado is a questions and answers site for your enterprise or community, your “knowledge base on the cloud”. It makes sure questions never get asked twice by making the information flow.

Scoold is inspired by StackOverflow and implements most of its features. You can ask and answer questions, upvote and downvote posts, earn badges and reputation. Each edit creates an new revision, making it easy to follow the history of edits. Scoold is optimized for the cloud. You can simply click the 'Deploy to Heroku' button and get up-and-running in minutes. You can deploy it to your favorite PaaS, too.

Glisser makes presentations interactive – it takes regular PowerPoint or Keynote slide decks and pushes them out live to audience mobile devices, slide-by-slide, as they are presented. It then enables members of the audience to interact with the presenter or each other, and collects valuable feedback. Attendees can also electronically mark-up the slides with notes, and keep them for future reference.

AnswerCart provide a community platform to the businesses which can be integrated with websites or mobile apps. Using community, users can engage in Q&A, blogging and socialization or in short we help organizations to build their own forum like Quora or StackOverflow.

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

Interaction platform for programming enthusiasts, learners, and experts to solve problems. Fast and inexpensive solutions to your programming problems. People with no prior knowledge of the programming knowledge can start from here and reach an expertise level. Doubts are also solved in minimum time.

BitAsker is a paid question and answer plateform using Bitcoin ... a user can win money by answering a question.

Eris Solver implements an innovative way to solve complex problems by adapting the Osborn's methodology (brainstorming technique) to a Problem Tree Analysis and by channelling Collective Intelligence.