coComment is a service for managing, powering and researching conversations online. When using coComment, you can keep track of your comments across any site, share them with friends, and get notified when you get a response.Discontinued
Seems to be discontinued as of April 2 2013.
A commenting server similar to Disqus and IntenseDebate
Licensed under AGPL: https://github.com/phusion/juvia/blob/master/LICENSE.TXT.Discontinued
Per project's README: Juvia is currently unmaintained. See https://github.com/phusion/juvia
IntenseDebate is the premier commenting system available on the Internet for blogs and websites. IntenseDebate comments enhances and encourages conversation on your blog or website. With IntenseDebate you can give your blog readers the opportunity to better engage your blogs...
Livefyre was an embeddable real-time commenting platform that turned comments on any site into live conversations, increased the quality of those conversations, and drove traffic to content around the web.Discontinued
Livefyre was acquired by Adobe and integrated into the Adobe Experience Manager. The Community Comments feature is being discontinued: https://livefyre.zendesk.com/hc/en-us/articles/215571503-Details-and-important-dates