Twinity is a 3D online world that links the real with the virtual world based on realistic replicas of the world’s most vibrant metropolises in 3D.

Croquet is a powerful new open source software development environment for creating and deploying deeply collaborative multi-user online applications on multiple operating systems and devices. Derived from Squeak, it features a peer-based network architecture that supports communication, collaboration, resource sharing, and synchronous computation between multiple users on multiple devices. Using Croquet, software developers can create and link powerful and highly collaborative cross-platform multi-user 2D and 3D applications and simulations - making possible the distributed deployment of very large scale, richly featured and interlinked virtual environments.

Worlds is the pioneering platform in 3D virtual communities and rich immersive environments. Launching in 1994, Worlds leverages its patented proprietary technology in partnership with brand leaders in specific market segments to offer members multi-user environments that have interactive Avatars, rich media graphics, text chat, voice-to-voice chat, video and e-commerce.

The 3D communities allow visitors to interact with each other, teleport throughout the Worlds environment as well as participate in shared experiences. Besides partnering with existing content providers that have strong brands and an existing following, Worlds also encourages individuals to create their own virtual spaces, communities and unique Avatars with easy-to-use tools. Worlds was and remains true “social networking” well before the term became mainstream.

Active Worlds, the web's most powerful Virtual Reality experience, lets you visit and chat in incredible 3D worlds that are built by other users. Think you have what it takes to build your own world, Virtual Reality game or training software? Active Worlds is the place for you, where in minutes you can create fascinating 3D worlds that others can visit and chat in. Our White Label solution allows you to custom brand your virtual world and host it on your servers.

OpenSimulator is a 3D Application Server. It can be used to create a virtual environment (or world) which can be accessed through a variety of clients, on multiple protocols. OpenSimulator allows you to develop your environment using the technologies you feel work best - we've designed the software to be easily extendable through loadable modules to build completely custom configurations. OpenSimulator is released under a BSD License, making it both open source, and commercially friendly to embed in products.

realXtend speeds up the development of the global standardized 3D internet of virtual worlds by making the best technology available to everyone, and entirely free of charge. The true value of the interconnected 3D worlds is in the applications, not the platform.

Do not pay for the technology, invest in content. realXtend can reach the highest possible number of users and developers because it is open source.

realXtend offers a free open source virtual world platform . You can create your own applications using it as a base.

A metaverse viewer project with an emphasis on usability. Derivative of second life.

The Hippo OpenSim Viewer is a modified Second Life viewer, targeted at OpenSim users. It allows building up to a height of 10,000 m, scaling prims up to 256x256x256 m and other exciting features. More specific OpenSim features are under development. For more details please refer to the features page or give it a try straight from the downloads page.

Content in Openlife is created by users, this is the 'created by users, for users' concept. You can choose many paths for your virtual life, as an entrepreneur earning credits, a designer, a builder, a player, a diva, a DJ and more, freedom is yours. Enjoy your new virtual life, the Openlife is currently a working beta, so we have bumps but it's plenty of fun!

All you need is to register & create your free avatar, next download the '3DXviewer' to connect to the live world. You can be a part of this virtual community in just minutes, start now and join over 50,000 registered users in the Openlife Beta Virtual World.

Virtual life community. Connect your real self with your avatars; keep track of poeple on other worlds.

3D chat world with emphasis on avatar realism.

Nothing to download! Easy to use. Anyone can create a world. Quickly import and share your own creations. The BBC has a review