Start on Android by Google - Developer program to optimize your app before you launch
MkDocs - Project documentation with Markdown.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
GitBook - Modern Publishing, Simply taking your books from ideas to finished, polished books.
Visage - Visage is a new platform that enables non-designers to easily create beautiful, on-brand visual content such as data visualization, reports & much more
Slate API Docs Generator - Create beautiful, intelligent, responsive API documentation.