What are some alternatives?
When comparing Hexo and GatsbyJS, you can also consider the following products
Jekyll - Jekyll is a simple, blog aware, static site generator.
Nikola - Nikola is s static site generator tool written in Python.
Grav - The modern open source flat-file CMS
Ghost - Ghost is a fully open source, adaptable platform for building and running a modern online publication. We power blogs, magazines and journalists from Zappos to Sky News.
Hugo - Hugo is a general-purpose website framework for generating static web pages.
Wintersmith - Flexible, minimalistic, multi-platform static site generator built on top of node.js