Yep was going to say Reveal.js too. Earlier today someone posted an integration of Jupyter Notebooks with Reveal.js which looks pretty cool. https://github.com/datitran/jupyter2slides

There is an Emacs org-reveal[0] package that shall help you use it like WYSIWYG.

[0] https://github.com/yjwen/org-reveal/

The thing that always got me with reveal was nested slides and whether I was supposed to nav with the arrow keys or not. Turns out if you ONLY hit the space bar it will visit the slides in-order. I guess.

But I think the OP was looking for a zoomable surface, which reveal doesn't offer.

http://lab.hakim.se/reveal-js/#/

FYI: Slide Show (S9) also has a reveal.js template/theme pack so you can write your talks / slides in plain text with markdown formatting conventions. See https://github.com/slideshow-templates/slideshow-reveal.js

+1 for reveal.js. I use it for several professional training courses that we deliver, as well as conference presentations.

Given that it's HTML/Markdown, it's great to use in a team with version control. I know folks that have extended it to allow SVG animations.

slides.com is a front-end for reveal.js, made by the authors of reveal. Nowadays I just write reveal.js directly, but it was nice to have a GUI when I was first getting started

Can it do boxes and arrows stuff?