Reveal.js - A framework for easily creating beautiful presentations using HTML
Typora - A minimal Markdown reading & writing app.
Prezi - Welcome to Prezi, the presentation software that uses motion, zoom, and spatial relationships to bring your ideas to life and make you a great presenter.
Dillinger - joemccann has 95 repositories available. Follow their code on GitHub.
Google Slides - Create a new presentation and edit it with others at the same time — from your computer, phone or tablet. Free with a Google account.
StackEdit - Full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.