From the description (“make any website editable inline”), I expected this to be a browser extension or similar that would allow you to change the content on any website. I find instead that it’s a CMS sort of thing, and is just a way of editing content on sites that you control and set it up on.

But in case anyone wants the other:

  document.designMode = 'on'

It’s pretty cool. Basically it makes the whole page a contenteditable. Many years ago browsers had more involved UI wrapped around design mode (which was also exposed in the menu), with a formatting toolbars and such.