Stack Overflow

stack overflow, part of stack exchange , is a free, community-driven, reputation-based q & a site for computer programmers.

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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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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.

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Shapado

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.

Freemium Linux Web

Shrtct

Shrtct is a productivity tool for teams, providing in-context communication (chit chat free!) via Shrtct Hashes.

Free Personal 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

AllAnswered

AllAnswered.com is a free hosted service for any community to build their own Stack Overflow-like Q&A board. Check it out to see how easy it is to have your own Stack Overflow.

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Askalot

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

Free Open Source Self-Hosted