A lot of the various online link/news-posting communities provide their back-end code as open source. Here are some:<p>kuro5hin: <a href="https://github.com/BlastarIndia/scoop" rel="nofollow">https://github.com/BlastarIndia/scoop</a><p>slasdot: <a href="https://sourceforge.net/p/slashcode/git/ci/live/tree/" rel="nofollow">https://sourceforge.net/p/slashcode/git/ci/live/tree/</a><p>reddit: <a href="https://github.com/reddit" rel="nofollow">https://github.com/reddit</a>
I run HelloBox<p><a href="https://www.hellobox.co" rel="nofollow">https://www.hellobox.co</a><p>It was started as "Create your own HackerNews clone" tool. It lets you create a HN-type community. Please check it out.
The code for HN is available at <a href="http://www.arclanguage.org/arc3.1.tar" rel="nofollow">http://www.arclanguage.org/arc3.1.tar</a>.