Gatsby is a static CMS, so something like WordPress, but static - without database.

Why Gatsby? No database means the most simple hosting is enough and of course because of that it's much quicker than classic CMS like WordPress or Joomla. It's made on React and that makes him quite fast - only front page is loaded, other content and other pages are loaded extremely fast without another page reload.

It's not as complex as WordPress, but for something simplier like blog it's a very good choise. There is a significant drawback - the content has to be in Markdown file and every time the content changes, the whole site needs to be rebuild. But that could be solved by using something like Contentful.com