Question2Answer - Stackoverflow styled, PHP base Q&A system

•    PHP

A Q&A site helps your online community to share knowledge. No matter what your area of interest, people with questions can get super answers fast.

OSQA - Stackoverflow like QA system in Python

•    Python

OSQA is the open source Q&A system. It 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. OSQA is built and maintained by a team of developers who share an interest in making a great, free, open source Q&A system available to everyone. The OSQA project is hosted and financially supported by DZone, Inc.

HashOver 2.0 - PHP based Comment System

•    PHP

HashOver is a PHP comment system intended as a replacement for services like Disqus. HashOver adds a "comment section" to any website, by placing a few simple lines of JavaScript or PHP to the source code of any webpage. HashOver is a self-hosted system and allows completely anonymous comments to be posted, the only required information is the comment itself.

Commento - A lightweight, open-source, privacy-focussed comment engine alternative to Disqus.

•    Go

Commento is a comment engine. You can embed it on your blog, news articles, and any place where you want your readers to add comments. It's lightweight and simple, allowing for lightning fast page loads. It's privacy-focused because that's the way comment engines should be. Embedding comments on your blog on why Vim is the greatest editor shouldn't inject tons of ads and tracking scripts into your reader's browser.

Isso - a Disqus alternative

•    Python

Isso is a lightweight commenting server similar to Disqus. It allows anonymous comments, maintains identity and is simple to administrate. It uses JavaScript and cross-origin ressource sharing for easy integration into (static) websites.

Juvia - A commenting server similar to Disqus and IntenseDebate

•    Ruby

Juvia is an open source commenting system. It allows you to outsource your commenting needs to an external system so that you don't have to build your own commenting system for each website or each web app. Embedding a Juvia commenting page only involves pasting a JavaScript snippet into your web page.

talkatv - An open source commenting system

•    Python

talkatv is a comment service much like DISQUS or IntenseDebate. talkatv is embedded on any page and uses XMLHttpRequest level 2 and Cross-Origin Resource Sharing to post the comment back to the server.

shapado - Stackoverflow like QA system in Ruby

•    Ruby

Shapdo is a open source Q&A system similar to StackOverflow, Yahoo Answers and some others. It has all the features you would want for a good social Q&A site plus a few more (theming, custom editor), email alerts per questions, following favorite users and one of our key feature is i18n for the UI and for the questions. Tagging and Badging support.

Mouthful - Self-hosted alternative to Disqus

•    Go

Mouthful is a lightweight commenting server written in GO and Preact. It's a self hosted alternative to disqus that's ad free. It supports multiple database support(sqlite, mysql, postgres, dynamodb), Server side caching to prevent excessive database calls, Rate limiting, Honeypot feature, to prevent bots from posting comments, Migrations from existing commenting engines(isso, disqus) and lot more.

Cusdis - Open source, lightweight (~5kb gzip), privacy-friendly alternative to Disqus

•    Typescript

Open source, lightweight (~5kb gzip), privacy-friendly alternative to Disqus. It is not designed to be a complete alternative to Disqus. It's aim is to implement a minimalist and embeddable comment system for small websites (such as your static blog).

remark - comment engine

•    Go

Remark42 is a self-hosted, lightweight, and simple (yet functional) comment engine, which doesn't spy on users. It can be embedded into blogs, articles or any other place where readers add comments. Authentication handled by external providers. You should setup oauth2 for all (or some) of them to allow users to make comments. It is not mandatory to have all of them, but at least one should be correctly configured.

Scoold - Stack Overflow clone in Java

•    Java

Scoold is a Q&A platform. The primary goal of this project is educational but it can also work great as a Q&A/support section for your website. Its feature include Full text search, Database-agnostic, optimized for cloud deployment, Distributed object cache, Reputation and voting system with badges, Email notifications for post replies and comments, Social login (Facebook, Google, GitHub, LinkedIn, Microsoft, Twitter) with Gravatar support.

Discourse - Discussion Platform like Stackoverflow

•    Ruby

Discourse is a platform for community discussion. Whenever you need a mailing list, a forum to discuss something, a chat room where you can type paragraphs, consider Discourse. It provides a flattened discussion, which avoids the pains of threaded forums, and delivers a more robust, intuitive interface to join a conversation at any point.

Comments App - A real-time, markdown-enabled comment engine powered by leveldb with oauth support

•    Javascript

A real-time comment engine with support for anonymous or authenticated posts.

giscus - A comments system powered by GitHub Discussions

•    Typescript

A comments system powered by GitHub Discussions. Let visitors leave comments and reactions on your website via GitHub. It is heavily inspired by utterances. It does not require database, all data is stored in GitHub Discussions. It is Extensively configurable and supports Custom themes, Multiple languages.

SharePoint Comments Anywhere

This is a very simple project which provides a commenting web part and a list template with the instance to store user's comments. SharePoint OTB only provides commenting capability on the Blog sites where users add their posts and anyone can view the page and add comments....

LampCMS - Q&A program in PHP

•    PHP

Lampcms is an full-featured Open Source Question and Answers web program with support for social web with the integration with Facebook and Twitter. Lampcms is tag-based, all questions are tagged by the author and can then be grouped by tag.

Qwench - PHP StackOverflow Clone

•    PHP

Qwench is a PHP/mySQL based StackOverflow clone. It allows users to post questions and answers and also to post an article as a knowledge-base. It supports points system similar to StackOverflow.

ASKBOT

•    Python

ASKBOT is a open source Q&A system similar to 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.

Misago - Full featured forum application standing on shoulders of Django

•    Python

Misago aims to be complete, featured and modern forum solution that has no fear to say 'NO' to common and outdated opinions about how forum software should be made and what it should do.