Platforms

=Virtual World Platforms:=

Open source

 * OpenSim
 * Unity 3D and Jibe
 * Open Wonderland
 * realXtend
 * Open Cobalt

Proprietary
=Open Source Worlds:=
 * ActiveWorlds
 * Second Life
 * Telepresence

OpenSim is available as a BSD Licenced download or as a commercially hosted world.
>> This reference guide is relevant for developers and VW implementers, not necessarily for users. >> A birds-eye view of the Hypergrid. >>
 * Voice Options for OpenSim
 * The Whisper voice service is a free and open source but only currently available for the Windows platform (Sept 2010). It is based on Mumble.
 * TeamSpeak for OpenSim
 * Vivox offers free voice services to small OpenSim grids. Article
 * FreeSwitch voice
 * Hypergrid, a system for teleporting between OpenSim grids. Reference guide for the Hypergrid ( It's a work in progress and it will likely change as the Simian folks reimplement this in Apache+PHP, and as we continue to strengthen security.

There are many OpenSim public grids and some education grids.
 * ReactionGrid is a G rated public grid with lots of support and discount for educators. You can use their public areas or purchase your own regions from the ReactionGrid Outpost. Your grids can be connected to ReactionGrid or private.
 * IBM's ScienceSim is a free OpenSim based grid  for the high performance computing community. It can be used for education, collaboration and visualization. Content in ScienceSim is created by its users, for its users.
 * OSGrid

Marketplaces for OpenSim resources
 * Rexxed @http://www.rexxed.com/ (mainly xml files for upload to opensim via meerkat, open for creators to sell their goods)
 * My Opensim @http://myopensim.com/ (mainly designed to serve content to the Myopengrid but does have some full perms stuff)
 * ReactionGrid's Outpost http://outpost.reactiongrid. com/ (more highend tools that everyday shopping - but includes some great stuff)
 * SLapt @http://slapt.me/ (which is an independent shopping destination for SL primarily, but allows creators to specify their work as 'for opensim ' as well as in SL
 * Total Avatar Shop http://www. totalavatarshop.com/ which will deliver to ReactionGrid or Second Life.

Wonderland
Proprietary Worlds=
 * ==ActiveWorlds==
 * ==Second Life==
 * ==Teleplace==