Open Cobalt is a free and open source virtual workspace browser and construction toolkit for accessing, creating, and publishing hyperlinked multi-user virtual environments. Powered by Croquet technology, Open Cobalt uses an ordered group messaging protocol that provides participants with a shared, consistently replicated, real time, computationally dynamic set of multi-participant virtual workspaces and eliminates the need for virtual world servers. It also makes it very simple to create and securely share deeply collaborative virtual workspaces that run on all major software operating systems. Without any licensing fees, users and developers can freely build and share highly capable multi-user virtual workspaces, game-based learning and training environments, or even just a place to share and meet with friends.