Croquet: A Collaboration Architecture

Alan Kay, HP Labs

Seminar on People, Computers, and Design
Stanford University April 25, 2003

Croquet is a computer software architecture built from the ground up with a focus on deep collaboration between teams of users. It is a totally open, totally free, highly portable extension to the Squeak programming system, a modern variant of Smalltalk. Croquet is a complete development and delivery platform for doing real collaborative work. There is no distinction between the user environment and the development environment.

Croquet is also a totally ad hoc multi-user network. It mirrors the current incarnation of the World Wide Web in many ways, in that any user has the ability to create and modify a "home world" and create links to any other such world. But in addition, any user, or group of users (assuming appropriate sharing privileges), can visit and work inside any other world on the net. Just as the World Wide Web has links between the web pages, Croquet allows fully dynamic connections between worlds via spatial portals. The key differences are that Croquet is a fully dynamic environment, everything is a collaborative object, and Croquet is fully modifiable at all times.

Croquet is a joint project being developed by David A. Smith, Alan Kay, David P. Reed, and Andreas Raab. More information is available at:

Alan Kay is one of the pioneers of personal computing. In 1966 he helped invent "object-oriented programming" In 1967-9 he and Ed Cheadle invented the FLEX Machine, a very early modern desktop machine they called a "personal computer" which led to his design of the Dynabook, "a personal computer for children of all ages," in the form of a very portable notebook, with a flat-screen, stylus, wireless network, and local storage. At Xerox PARC in the 70s he invented Smalltalk, which was the first complete dynamic object oriented language, development, and operating system, and was one of the instigators for the first bitmap displays and the main inventor of the now ubiquitous overlapping windows, icons, point-click-and-drag user interface.
Most of his contributions from 1968 onwards have been the result of trying to invent and test better learning environments, mainly for children.
He has been a Xerox Fellow, Chief Scientist of Atari, Apple Fellow, Disney Fellow, and is now a Senior Fellow in HP Labs and President of Viewpoints Research Institute. He started his career as a professional jazz guitarist. Much of his show business experience combined music and theatrical production. Today he is an avid amateur classical pipe organist. His honors include: J-D Warnier Prix d'Informatique, ACM Systems Software Award, Computers & Communication Foundation Prize. He has been elected a Fellow of the American Academy of Arts and Sciences, the National Academy of Engineering, and the Royal Society of Arts.

View this talk on line at CS547 on Stanford OnLine

Titles and abstracts for all years are available by year and by speaker.

For more information about HCI at Stanford see

Overview Degrees Courses Research Faculty FAQ