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RDoc

ruby.github.io

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Spec score 8.1 #8 of 37 in Documentation Generators

What it is

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.

Spec sheet

Purpose
RDoc produces HTML and command-line documentation for Ruby projects, with `rdoc` and `ri` tools to generate and display it.Read 8 Oct 2026 · ruby.github.io
Support
The project directs users to CONTRIBUTING.md for filing bug reports.Read 8 Oct 2026 · ruby.github.io
License
RDoc is free software and may be redistributed under the terms in its license file.Read 8 Oct 2026 · ruby.github.io
Automation
The site documents generating RDoc through a Rake task and through a Ruby programmatic API.Read 8 Oct 2026 · ruby.github.io
Coverage reporting
The `rdoc -C` command reports documentation coverage, and `rdoc -C1` includes parameter names.Read 8 Oct 2026 · ruby.github.io
Documentation coverage
RDoc can report project documentation coverage with `rdoc -C`, with an option to include parameter names in the report.Read 8 Oct 2026 · ruby.github.io
Input formats
RDoc processes Ruby, C, and RBS source files, along with markup files.Read 8 Oct 2026 · ruby.github.io
Integration
Documentation can be generated using a Rake task or programmatically through the RDoc API.Read 8 Oct 2026 · ruby.github.io
Known limitation
Deleting a file that contains part of a class reopened across multiple files can temporarily remove the entire class from the preview store until another file is saved and reparsed.Read 8 Oct 2026 · ruby.github.io
License and warranty
RDoc describes itself as free software and states that it is provided as is without express or implied warranties.Read 8 Oct 2026 · ruby.github.io
Live preview
RDoc includes a local preview server that watches source files and refreshes the browser when they change.Read 8 Oct 2026 · ruby.github.io
Markup
RDoc supports RDoc markup, Markdown, RD, and TomDoc; the site recommends Markdown for standalone documentation and discourages new use of RD and TomDoc.Read 8 Oct 2026 · ruby.github.io
Preview server
RDoc includes a local preview server that watches source files and refreshes the browser when they change.Read 8 Oct 2026 · ruby.github.io
Preview server dependencies
The preview server uses Ruby’s built-in TCPServer and requires no external dependencies, WEBrick, or other gems.Read 8 Oct 2026 · ruby.github.io
Preview server security
The preview server has no HTTPS or HTTP/2 and is intended for local development preview only.Read 8 Oct 2026 · ruby.github.io
RBS support
RBS declarations can document classes, modules, methods, attributes, and constants, and can extend matching Ruby source documentation with comments and type signatures.Read 8 Oct 2026 · ruby.github.io
Release
RubyGems lists RDoc version 8.1.0, released September 28, 2026.Read 8 Oct 2026 · rubygems.org
Ruby requirement
RubyGems lists Ruby version 3.2.0 or newer as required for the current gem.Read 8 Oct 2026 · rubygems.org
Server dependency
The preview server uses Ruby's built-in TCPServer and requires no external gems.Read 8 Oct 2026 · ruby.github.io
Server limitation
The preview server has no HTTPS or HTTP/2 and is intended for local development preview only.Read 8 Oct 2026 · ruby.github.io
Themes
RDoc includes the Aliki theme by default, while its classic Darkfish theme is deprecated and the site says it will be removed in v9.0.Read 8 Oct 2026 · ruby.github.io
Warranty
The software is provided as is without express or implied warranties.Read 8 Oct 2026 · ruby.github.io

Plans and prices

RDoc Free Free software; no paid plans or usage limits stated Read 8 Oct 2026 · ruby.github.io

Every RDoc plan and price →

Strong points and limits

Strong points

  • Free software with no paid plans stated
  • Processes Ruby, C, and RBS sources
  • Local preview server refreshes after changes
  • Coverage reports include optional parameter names
  • Supports Rake and programmatic generation

Limits

  • Requires Ruby 3.2.0 or newer
  • Preview server has no HTTPS or HTTP/2
  • Darkfish theme is deprecated
  • Preview deletion can temporarily remove reopened classes

Who it suits

RDoc suits Ruby projects that need generated HTML and command-line API references from source and markup files. It also fits teams automating documentation through Rake or the RDoc API.

Verdict

RDoc combines source processing, coverage reporting, automation, and a local live preview in one free package. Its preview server is for local development, and the current gem requires Ruby 3.2.0 or newer.

Where Specifiction places it

Alternatives to RDocAll alternatives →