Editorially is described as 'Write. Rewrite. Share and discuss. Everything you need to make good writing great' and is an website in the News & Books category. There are more than 50 alternatives to Editorially, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Android. The best alternative is Joplin, which is both free and Open Source. Other great sites and apps similar to Editorially are Typora (Free), Mark Text (Free, Open Source), ghostwriter (Free, Open Source) and Markdown (Free, Open Source).
Monospace is a minimal notes and writing app, built from the ground up with a designed-for-touch UI. It get's rid of the standard editing features you'd find in standard writing and notes apps and replaces them with a modern-styled, essentials-only formatting popup.
#Markdown is a efficient markdown editor for OS X, iPhone and iPad. ##Features: live preview, sync scroll, auto save, powerful actions, custom themes and CSS, HTML export,math, enhanced CJK support and more.