Maintainers

Ownership in ruby/ruby is documented authoritatively in doc/maintainers.md. That file is consulted by the auto-review-request workflow (.github/auto_request_review.yml) to nominate reviewers when a PR is opened.

This page summarises the major subsystem owners. For default gems whose source is vendored from upstream gem repositories, the real maintainer is the upstream gem's owner.

Top-level

Area	Owner
Language core features and security	Yukihiro "Matz" Matsumoto
Evaluator (VM, eval)	Koichi Sasada (ko1)
Core classes (overall)	Yukihiro Matsumoto

Subsystems

Subsystem	Maintainer(s)
Garbage collector (gc/, gc.c)	Peter Zhu, Matt Valentine-House (the "GC team")
Parser (parse.y)	Yui Naruse (naruse), Yuichiro Kaneko (yui-knk)
Prism (prism/)	Kevin Newton, Shopify Prism team
Lrama (tool/lrama/)	Yuichiro Kaneko (yui-knk)
YJIT (yjit/)	Maxime Chevalier-Boisvert, Alan Wu, Takashi Kokubun, Aaron Patterson, Shopify YJIT team
ZJIT (zjit/)	Shopify YJIT/ZJIT team
Threads (thread.c, thread_pthread.c)	Koichi Sasada (ko1)
Ractor (ractor.c)	Koichi Sasada (ko1)
Fibers / coroutines (cont.c, coroutine/)	Samuel Williams (ioquatix), Koichi Sasada
Fiber Scheduler (scheduler.c)	Samuel Williams (ioquatix)
IO (io.c, io_buffer.c)	Samuel Williams (ioquatix)
Encoding / M17N (encoding.c, enc/)	Yui Naruse (naruse), Martin Dürst (duerst) for Unicode normalisation
Onigmo regex (reg*.c)	K. Takata, Akinori MUSHA, upstream Onigmo maintainers
Set (set.c, lib/set.rb)	Akinori MUSHA (knu)

Standard library (default gems)

Most default gems have an upstream repository; the maintainer there is the canonical owner. Selected mappings (full list in tool/sync_default_gems.rb's REPOSITORIES hash and doc/maintainers.md):

Gem	Upstream	Maintainer
rubygems / bundler	github.com/rubygems/rubygems	Hiroshi SHIBATA (hsbt) and the rubygems team
optparse	github.com/ruby/optparse	Nobuyoshi Nakada (nobu)
uri	github.com/ruby/uri	Aaron Patterson (tenderlove)
prism	github.com/ruby/prism	Kevin Newton
psych	github.com/ruby/psych	Aaron Patterson
json	github.com/ruby/json	Jean Boussier (byroot) and the json team
did_you_mean	github.com/ruby/did_you_mean	Yuki Nishijima
error_highlight	github.com/ruby/error_highlight	Yusuke Endoh (mame)
syntax_suggest	github.com/ruby/syntax_suggest	Schneems and contributors
irb	github.com/ruby/irb	aycabta and the IRB team
reline	github.com/ruby/reline	aycabta
rdoc	github.com/ruby/rdoc	the rdoc team
prettyprint / pp	upstream + here	Yuki Sonoda
pathname (Ruby + ext)	here	Tanaka Akira (akr)
mkmf (lib/mkmf.rb)	here	(no specific maintainer; nobu in practice)
unicode_normalize	here	Martin J. Dürst (duerst)

C extensions in ext/

Extension	Maintainer
ext/socket	Tanaka Akira (akr) — API changes need matz's approval
ext/openssl	Kazuki Yamaguchi (rhenium) and the openssl team
ext/digest	Akinori MUSHA (knu)
ext/pathname	Tanaka Akira (akr)
ext/coverage	Yusuke Endoh (mame)
ext/objspace	(no specific maintainer)
ext/ripper	(no specific maintainer)
ext/pty	(no specific maintainer)
ext/fiber	Samuel Williams
ext/monitor	Koichi Sasada
ext/win32	NAKAMURA Usaku (unak)
ext/zlib	(no specific maintainer; was UI Misuzu)
ext/strscan	upstream Sutou Kouhei (kou)
ext/stringio	Nobuyoshi Nakada
ext/etc, ext/fcntl	(legacy, low maintenance)

Platform maintainers

Per doc/maintainers.md's "Platform Maintainers" section:

Platform	Maintainer
Ubuntu / Debian	(community)
macOS	Yuta Saito (katei), Aaron Patterson
Windows MSVC	NAKAMURA Usaku (unak)
Windows MinGW	Lars Kanis
Solaris / illumos	(community)
AIX	(community)
WASM / WASI	Yuta Saito (katei)

Branch maintainers

Stable releases of older Ruby branches are cut by per-branch maintainers. The current list is at the Release Engineering wiki page. Recent maintainers:

Branch	Maintainer
master (4.1 dev)	All committers; Yui Naruse coordinates releases
ruby_3_4	Yui Naruse (naruse)
ruby_3_3	Yui Naruse
ruby_3_2	Hiroshi SHIBATA (hsbt)

How review-request automation works

When you open a PR, GitHub Actions consults .github/auto_request_review.yml and the labels mapped from doc/maintainers.md. Reviewers are auto-suggested based on which files the PR touches.

You can mention specific maintainers in the PR description if you want their attention, but the bot usually picks the right people based on paths.

How to update the list

The authoritative source is doc/maintainers.md. To update:

1. Edit doc/maintainers.md.
2. (If you're listed as a new owner of a path) update .github/auto_request_review.yml if your username isn't already mapped.
3. Open a PR.

The "3 months rule" applies: a maintainer who hasn't been active on their part for three months can be discharged. (See the cited ruby-core thread in the original document.)

See also

• doc/maintainers.md — full list (this page summarises it).
• .github/auto_request_review.yml — reviewer auto-assignment.
• .mailmap — historical author/email aliases (for git blame).
• tool/sync_default_gems.rb's REPOSITORIES hash — gem ↔ upstream-repo mapping.