Project Xanadu

Project Xanadu was the first computer project to include hypertext , in 1960. It also had various other features that were way ahead of its time such as version control and bi-directional linking.

https://en.wikipedia.org/wiki/Project_Xanadu

Due to various struggles inside the team and external factors, Xanadu gradually lost out to the World wide web. Still, it would prove to be influential and many different products replicated various parts of the initital specification, and expanded on them.

Here is an interesting thread blasting the problems of spinoffs of the xanadu project

And another post by the same author explaining Xanadu technical details