Do you need to write formulae and heavy mathematical notation in your paper? Or maybe you need to write entire parts of your paper in LaTeX or Markdown? Authorea's rich text editor is a true WYSIWYG editor (what you see is what you get), but it gives you the ability to include mathematics as well as LaTeX and Markdown. If you have to type a simple (yet beautiful) equation such as
\(e^{i\pi}+1=0\), or a full fledged equation in LaTeX, such as eq.
\ref{eqn:lat} (below), you can! Read this tutorial:
How to add mathematical equations and formulae.