Spacemacs is described as 'beautiful Emacs distribution designed for both GNU Emacs and Vim users' and is an app in the Development category. There are more than 25 alternatives to Spacemacs for a variety of platforms, including Mac, Linux, Windows, BSD and Android. The best alternative is Visual Studio Code, which is free. Other great apps like Spacemacs are Atom (Free, Open Source), Sublime Text (Free Personal), Vim (Free, Open Source) and VSCodium (Free, Open Source).
VS Code is more than just a code editor, it provides the tools and extensions to compile, debug, compare, refactor, and even manage code repositories all within a highly-customised development environment.
Neovim is a project that seeks to aggressively refactor Vim in order to: Simplify maintenance and encourage contributions. Split the work between multiple developers. Enable the implementation of new/modern user interfaces without any modifications to the core source.
Bluefish is a powerful editor targeted towards programmers and webdesigners, with many options to write websites, scripts and programming code. Bluefish supports many programming and markup languages, and it focuses on editing dynamic and interactive websites.
CudaText is a cross-platform text editor, written in Lazarus. It starts quite fast (0.5 sec with ~30 plugins on CPU Intel Core i3 3Hz). It is extensible by Python add-ons (plugins, linters, code tree parsers, external tools).
Haroopad is a markdown enabled document processor for creating web-friendly documents. You can author various formats of documents such as blog article, slide, presentation, report, and e-mail as if experts did.