Now that Diaspora, which is building an open-source distributed social network, has launched in private alpha, I figured it&'d be a good idea to remind you that there are several alternatives to that particular Facebook alternative, some of which have been around longer and in more advanced stages of development.

Note that there may be more initiatives that I haven&'t heard of or simply didn&'t or forgot to mention, so this is by no means an exhaustive list. Also, all of these deserve a full review, so I refrained from making quick-and-dirty comparisons between all of them.

(previous coverage, CrunchBase profile)

An initiative of Vodafone Group Research and Development, OneSocialWeb is being built on a foundation and uses a host of open source technologies &8211' it&'s primarily based on XMPP.

The initiators of OneSocialWeb say they were inspired by the visionaries behind other open Web standardization initiatives such as activitystrea.ms, portablecontacts, OAuth, OpenSocial, FOAF, XRDS, OpenID and others.

Tagline: free open decentralized social networking platform

Useful links: OSW roadmap, developer downloads and the code.

Video:

Still in active development, Appleseed aims to create an open source, fully distributed and decentralized social networking software suite.

When it&'s done, its website reads, users will be able to &''pick an Appleseed compatible site, sign up, connect with friends, send messages, share photos and videos and join discussions. And if you decide you don&'t like the site you&'re on, you&'ll be able sign up for another Appleseed compatible site and immediately reconnect with everyone in your network.

Tagline: The First Open Source + Distributed Social Networking Platform

Useful links: discussion forum, beta test site, source code and &8211' haha &8211' Facebook group.

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(CrunchBase profile)

Elgg provides a free to download and use open-source social networking engine that provides a framework on which to build all kinds of social environments, from social networks to an enterprise-ready internal collaborative or communication platform. Elgg runs on a combination of the Apache web server, MySQL database system and PHP.

Tagline: a powerful open source social networking engine

Useful links: download, plugin directory, community.

(previous coverage, CrunchBase profile)

An open-source social networking platform written in Ruby on Rails.

Useful links: source code (freely available under the MIT license), example site, wiki.

Also check out our ancient post: 34 More Ways to Build Your Own Social Network.

(Image via Flickr / opensourceway)