Project Xanadu: the original hypertext project

Founded 1960. Still not finished, and still the most complete alternative to the Web anyone has designed.

Xanadu began in 1960 as a Harvard term project: a writing system that could hold every version of a text, compare them side by side and connect any passage to any other. The name came later, from Coleridge's Kubla Khan, in 1966 or 1967 depending on which account you read. The goal never changed. Nelson wanted a worldwide library of electronic documents in which every connection is visible and every quotation remains attached to its origin.

The design has been stated as seventeen rules, among them: every document and every user is uniquely identified; a document can contain links, including virtual copies (transclusions), to any other document; links are visible and can be followed from both ends; every document can carry a royalty mechanism so authors are paid for any portion accessed, including transcluded portions; and the client-server protocol is an openly published standard.

The engineering history is long. Cal Daniels built a first demonstration in 1972 on a rented minicomputer that had to be returned. A summer at Swarthmore in 1979 brought Roger Gregory, Mark S. Miller and Stuart Greene, and with them tumblers, the addressing scheme that can name any span of any version of any document on any machine. Autodesk bought the technology in 1988 and let it go in August 1992. The source code was released as Udanax at the end of the 1990s. XanaduSpace, a viewer for parallel documents with drawn connections, appeared in 2007. OpenXanadu, a working deliverable, shipped in 2014, fifty-four years in.

In June 1995 Wired published Gary Wolf's The Curse of Xanadu, which opens by calling it the longest-running vaporware story in the history of the computer industry. Nelson answered with a rebuttal on his site and, in 2019, a feature-length video. The fair reading is that both things are true: the full system was never delivered, and the design it describes still names what the Web lacks. Werner Herzog put him on screen in 2016 for his persistence. xanadu.com, updated in his own hand, still says Founded 1960 * The Original Hypertext Project.

The seventeen rules

As summarized in Wikipedia's Project Xanadu article from the project's own statements.

1. Every Xanadu server is uniquely and securely identified.
2. Every Xanadu server can be operated independently or in a network.
3. Every user is uniquely and securely identified.
4. Every user can search, retrieve, create and store documents.
5. Every document can consist of any number of parts, each of which may be of any data type.
6. Every document can contain links of any type, including virtual copies (transclusions), to any other document in the system accessible to its owner.
7. Links are visible and can be followed from all endpoints.
8. Permission to link to a document is explicitly granted by the act of publication.
9. Every document can contain a royalty mechanism at any desired degree of granularity to ensure payment on any portion accessed, including virtual copies (transclusions) of all or part of the document.
10. Every document is uniquely and securely identified.
11. Every document can have secure access controls.
12. Every document can be rapidly searched, stored and retrieved without user knowledge of where it is physically stored.
13. Every document is automatically moved to physical storage appropriate to its frequency of access from any given location.
14. Every document is automatically stored redundantly to maintain availability even in case of a disaster.
15. Every Xanadu service provider can charge their users at any rate they choose for the storage, retrieval and publishing of documents.
16. Every transaction is secure and auditable only by the parties to that transaction.
17. The Xanadu client-server communication protocol is an openly published standard. Third-party software development and integration is encouraged.

Sources: Wikipedia, Project Xanadu; xanadu.com; Wired, June 1995. Where this page paraphrases him, the paraphrase is ours and the source is his.