It runs on L̶o̶t̶u̶s̶S̶c̶r̶i̶p̶t̶ JavaScript. Speaking of, Mitch Kapor's 1984 memo is turning 40 this year:
> With the formal commencement of the "Notes" project upon us, it
seemed appropriate to set down a few brief notions about the project, its scope, and its strategic importance to Lotus. This material should be regarded as more than highly confidential.
> With the formal commencement of the "Notes" project upon us, it seemed appropriate to set down a few brief notions about the project, its scope, and its strategic importance to Lotus. This material should be regarded as more than highly confidential.
https://web.archive.org/web/20180225100127/http://www.kapor....
Also discussed previously: https://news.ycombinator.com/item?id=13168969