In December 1995, while still at Apple, Kay collaborated with many others to start the open source Squeak version of Smalltalk, and he continues to work on it. As part of this effort, in November 1996, his team began research on what became the Etoys system. More recently he started, along with David A. Smith, David P. Reed, Andreas Raab, Rick McGeer, Julian Lombardi and Mark McCahill, the Croquet Project, an open source networked 2D and 3D environment for collaborative work.