Nikola is described as 'static website and blog generator. Its original goal is to create blogs, but it supports most kind of sites and can be used as a CMS, as long as what you present to the user is your own content instead of something the user generates' and is an app in the Development category. There are more than 10 alternatives to Nikola for a variety of platforms, including Self-Hosted solutions, Mac, Windows, Linux and Online / Web-based. The best alternative is Ghost. It's not free, so if you're looking for a free alternative, you could try Grav or Jekyll. Other great apps like Nikola are Hugo (Free, Open Source), Read The Docs (Free, Open Source), Pelican (Free, Open Source) and Hexo (Free, Open Source).
Grav is an easy to use, yet powerful, opensource CMS that requires no database. In a nutshell, installing Grav is a matter of unzipping the file. It is fast, has sophisticated caching, and a light footprint for optimal performance.
Jekyll is a simple, blog aware, static site generator. It takes a template directory (representing the raw form of a website), runs it through and Liquid converters, and spits out a complete, static website suitable for serving with Apache or your favorite web server.
Read the Docs hosts documentation for the open source community. It supports Sphinx docs written with reStructuredText, and can pull from your Subversion, Bazaar, Git, and Mercurial repositories. The code is open source, and available on github.
Hakyll is a Haskell library for generating static sites, mostly aimed at small-to-medium sites and personal blogs. It is written in a very configurable way and uses an xmonad-like DSL for configuration.