RDoc vs Sphinx

RDoc is free software for producing Ruby project documentation as HTML pages and command-line reference output. The `rdoc` command generates documentation, while `ri` displays it. It processes Ruby, C, and RBS source files, plus RDoc markup, Markdown, RD, and TomDoc documents. RBS declarations can describe classes, modules, methods, attributes, and constants, and can add comments or type signatures to matching Ruby source documentation. A local preview server watches source files and refreshes the browser after changes. It uses Ruby’s built-in TCPServer and needs no external gems, but provides neither HTTPS nor HTTP/2 and is intended only for local previews. RDoc reports documentation coverage with `rdoc -C`, or includes parameter names with `rdoc -C1`. Generation can be automated through Rake or the RDoc API. Aliki is the default theme; Darkfish is deprecated. Ruby 3.2.0 or newer is required for the current gem.

Sphinx is a free Python application that generates technical documentation from structured text. Authors can use reStructuredText or MyST Markdown; Markdown requires installing MyST-Parser separately. Built-in builders produce HTML, LaTeX for PDF, ePub, manual pages, Texinfo, and plain text. References can link sections, figures, tables, citations, glossaries, and code objects within one project or across projects. The autodoc extension imports documented modules and includes material from their docstrings. Themes and extensions, both built-in and third-party, add options such as diagrams, doctests, and API documentation. Other built-in extensions provide GitHub Pages publishing, Graphviz graphs, and intersphinx links. Sphinx also supports gettext-based translation and full-text search. It can be installed through Python and platform package managers, Docker, or from source, then deployed to services such as Read the Docs, GitHub Pages, GitLab Pages, Netlify, or self-hosted servers. Its code is released under the two-clause BSD license, and the project is community supported.