Reactacular is described as 'Share and react freely' and is an website in the Social & Communications category. There are more than 10 alternatives to Reactacular, not only websites but also apps for a variety of platforms, including Android, iPhone, iPad and Android Tablet. The best alternative is Reddit, which is free. Other great sites and apps similar to Reactacular are Stack Exchange (Free), Hacker News (Free), SaidIt.net (Free, Open Source) and Digg (Free).
Reddit (stylized in its logo as reddit) is an American social news aggregation, web content rating, and discussion website. Registered members submit content to the site such as links, text posts, and images, which are then voted up or down by other members.
Uncensored free speech alternative to the extreme Reddit and Voat forums, democratically civilized by Graham's Debate Pyramid, no illegal transactions nor porn. Truth-seeking anti-corruption news are among the popular themes. Android app, iOS soon.
News for nerds, stuff that matters. Slashdot (aka /.) is a technology-related news and discussion site with a focus on Linux, free and open source software and information freedom and privacy issues. The software it runs on, called Slashcode, is open source.