diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0d2d2ec83e4..408fab29045 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,9 +13,6 @@ jobs:
     strategy:
       matrix:
         include:
-          - os: ubuntu-latest
-            ruby: "3.1"
-            task: "--include-spec"
           - os: ubuntu-latest
             ruby: "3.2"
             task: "--include-spec"
@@ -24,13 +21,16 @@ jobs:
             task: "--include-spec"
           - os: ubuntu-latest
             ruby: "3.4"
+            task: "--include-spec"
+          - os: ubuntu-latest
+            ruby: "4.0"
             task: "--include-spec --include-yardoc --include-build"
             rubyopt: "--enable-frozen-string-literal --debug-frozen-string-literal"
           - os: macos-latest
-            ruby: "3.4"
+            ruby: "4.0"
             task: "--include-spec"
           - os: windows-latest
-            ruby: "3.4"
+            ruby: "4.0"
             task: "--include-spec"
       fail-fast: false
     runs-on: ${{ matrix.os }}
diff --git a/.github/workflows/generate-updates.yml b/.github/workflows/generate-updates.yml
index 5beb9acb97b..3af16b3fe7d 100644
--- a/.github/workflows/generate-updates.yml
+++ b/.github/workflows/generate-updates.yml
@@ -15,10 +15,10 @@ jobs:
     steps:
       - name: Checkout repo
         uses: actions/checkout@v4
-      - name: Install Ruby 3.4
+      - name: Install Ruby 4.0
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
       - name: Install tools
         run: |
           gem install --no-document toys
diff --git a/.github/workflows/release-freeze.yml b/.github/workflows/release-freeze.yml
index eaa72a33a49..6d7a08aa9f8 100644
--- a/.github/workflows/release-freeze.yml
+++ b/.github/workflows/release-freeze.yml
@@ -11,10 +11,10 @@ jobs:
     steps:
       - name: Checkout repo
         uses: actions/checkout@v4
-      - name: Install Ruby 3.4
+      - name: Install Ruby 4.0
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
       - name: Install tools
         run: |
           gem install --no-document toys
diff --git a/.github/workflows/release-unfreeze.yml b/.github/workflows/release-unfreeze.yml
index a5274c0859a..4b2201fe3fe 100644
--- a/.github/workflows/release-unfreeze.yml
+++ b/.github/workflows/release-unfreeze.yml
@@ -11,10 +11,10 @@ jobs:
     steps:
       - name: Checkout repo
         uses: actions/checkout@v4
-      - name: Install Ruby 3.4
+      - name: Install Ruby 4.0
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
       - name: Install tools
         run: |
           gem install --no-document toys
diff --git a/.github/workflows/weekly-generate-updates.yml b/.github/workflows/weekly-generate-updates.yml
index bbc9bc20927..7df8997424c 100644
--- a/.github/workflows/weekly-generate-updates.yml
+++ b/.github/workflows/weekly-generate-updates.yml
@@ -12,10 +12,10 @@ jobs:
     steps:
       - name: Checkout repo
         uses: actions/checkout@v4
-      - name: Install Ruby 3.4
+      - name: Install Ruby 4.0
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.4"
+          ruby-version: "4.0"
       - name: Install tools
         run: |
           gem install --no-document toys
diff --git a/Gemfile b/Gemfile
index f58c7a70acf..9ba5476bf22 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,7 @@
 source 'https://rubygems.org'
 
-gem "rake", "~> 13.0"
 gem "gems", "~> 1.2"
+gem "irb", "~> 1.17"
+gem "ostruct", "~> 0.5.5"
+gem "rake", "~> 13.0"
+gem "syslog", "~> 0.4.0"
diff --git a/google-apis-core/Gemfile b/google-apis-core/Gemfile
index de00a5d3130..59a0a45d00b 100644
--- a/google-apis-core/Gemfile
+++ b/google-apis-core/Gemfile
@@ -12,8 +12,11 @@ group :development do
   gem 'launchy', '~> 2.4'
   gem 'dotenv', '~> 2.0'
   gem 'fakefs', '>= 1.0', '< 4', require: "fakefs/safe"
+  gem "fiddle", "~> 1.1"
   gem 'google-id-token', '~> 1.3'
   gem 'os', '~> 0.9'
+  gem 'ostruct', '~> 0.5.5'
+  gem "irb", "~> 1.17"
   gem 'rmail', '~> 1.1'
   gem 'redis', '>= 3.2', '< 5.0.8'
   gem 'logging', '~> 2.2'
diff --git a/google-apis-core/google-apis-core.gemspec b/google-apis-core/google-apis-core.gemspec
index fb6e5d4d1e2..f5b4bf8efc7 100644
--- a/google-apis-core/google-apis-core.gemspec
+++ b/google-apis-core/google-apis-core.gemspec
@@ -19,7 +19,7 @@ Gem::Specification.new do |gem|
   gem.files = Dir.glob("lib/**/*.rb") + Dir.glob("*.md") + [".yardopts"]
   gem.require_paths = ["lib"]
 
-  gem.required_ruby_version = '>= 3.1'
+  gem.required_ruby_version = '>= 3.2'
   gem.add_runtime_dependency "representable", "~> 3.0"
   gem.add_runtime_dependency "retriable", "~> 3.1"
   gem.add_runtime_dependency "addressable", "~> 2.8", ">= 2.8.7"
diff --git a/google-apis-generator/Gemfile b/google-apis-generator/Gemfile
index a300a6c4336..8a379982217 100644
--- a/google-apis-generator/Gemfile
+++ b/google-apis-generator/Gemfile
@@ -12,8 +12,11 @@ group :development do
   gem 'launchy', '~> 2.4'
   gem 'dotenv', '~> 2.0'
   gem 'fakefs', '>= 1.0', '< 3', require: "fakefs/safe"
+  gem "fiddle", "~> 1.1"
   gem 'google-id-token', '~> 1.3'
   gem 'os', '~> 0.9'
+  gem "ostruct", "~> 0.5.5"
+  gem "irb", "~> 1.17"
   gem 'rmail', '~> 1.1'
   gem 'redis', '>= 3.2', '< 5.0.8'
   gem 'logging', '~> 2.2'
diff --git a/google-apis-generator/google-apis-generator.gemspec b/google-apis-generator/google-apis-generator.gemspec
index 30fc8ca3f35..022f042e6e9 100644
--- a/google-apis-generator/google-apis-generator.gemspec
+++ b/google-apis-generator/google-apis-generator.gemspec
@@ -20,7 +20,7 @@ Gem::Specification.new do |gem|
   gem.executables = ["generate-api"]
   gem.require_paths = ["lib"]
 
-  gem.required_ruby_version = ">= 3.1"
+  gem.required_ruby_version = ">= 3.2"
   gem.add_runtime_dependency "activesupport", ">= 5.0"
   gem.add_runtime_dependency "gems", "~> 1.2"
   gem.add_runtime_dependency "google-apis-core", ">= 0.15.0", "< 2.a"
diff --git a/google-apis-generator/lib/google/apis/generator/templates/gemspec.tmpl b/google-apis-generator/lib/google/apis/generator/templates/gemspec.tmpl
index b7daced4964..b6c740d4eab 100644
--- a/google-apis-generator/lib/google/apis/generator/templates/gemspec.tmpl
+++ b/google-apis-generator/lib/google/apis/generator/templates/gemspec.tmpl
@@ -28,6 +28,6 @@ Gem::Specification.new do |gem|
   gem.files = Dir.glob("lib/**/*.rb") + Dir.glob("*.md") + [".yardopts"]
   gem.require_paths = ["lib"]
 
-  gem.required_ruby_version = '>= 3.1'
+  gem.required_ruby_version = '>= 3.2'
   gem.add_runtime_dependency "google-apis-core", ">= 0.15.0", "< 2.a"
 end
diff --git a/google-apis-generator/lib/google/apis/generator/templates/overview.md.tmpl b/google-apis-generator/lib/google/apis/generator/templates/overview.md.tmpl
index 7899ef06d28..d35180d667b 100644
--- a/google-apis-generator/lib/google/apis/generator/templates/overview.md.tmpl
+++ b/google-apis-generator/lib/google/apis/generator/templates/overview.md.tmpl
@@ -83,7 +83,7 @@ The [product documentation](<%= api.documentation_link %>) may provide guidance
 
 ## Supported Ruby versions
 
-This library is supported on Ruby 3.1+.
+This library is supported on Ruby 3.2+.
 
 Google provides official support for Ruby versions that are actively supported by Ruby Core -- that is, Ruby versions that are either in normal maintenance or in security maintenance, and not end of life. Older versions of Ruby _may_ still work, but are unsupported and not recommended. See https://www.ruby-lang.org/en/downloads/branches/ for details about the Ruby support schedule.