diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..46f1c90
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,13 @@
+version: 2
+updates:
+  - package-ecosystem: bundler
+    directory: "/"
+    schedule:
+      interval: "daily"
+    open-pull-requests-limit: 10
+    ignore:
+      - dependency-name: "rubocop-lts"
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"
diff --git a/.github/workflows/unsupported.yml b/.github/workflows/unsupported.yml
new file mode 100644
index 0000000..3e13f86
--- /dev/null
+++ b/.github/workflows/unsupported.yml
@@ -0,0 +1,52 @@
+name: Unsupported (EOL) Ruby Matrix
+
+on:
+  push:
+    branches:
+      - 'master'
+    tags:
+      - '!*' # Do not execute on tags
+  pull_request:
+    branches:
+      - '*'
+  # Allow manually triggering the workflow.
+  workflow_dispatch:
+
+# Cancels all previous workflow runs for the same branch that have not yet completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name.
+  group: "${{ github.workflow }}-${{ github.ref }}"
+  cancel-in-progress: true
+
+jobs:
+  test:
+    name: Specs - Ruby ${{ matrix.ruby }}${{ matrix.name_extra || '' }}
+    if: "!contains(github.event.commits[0].message, '[ci skip]') && !contains(github.event.commits[0].message, '[skip ci]')"
+    env: # $BUNDLE_GEMFILE must be set at the job level, so it is set for all steps
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/${{ matrix.gemfile }}.gemfile
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - ruby: "3.0"
+            rubygems:  "3.3.27"
+            bundler: none
+            gemfile: vanilla
+          - ruby: "2.7"
+            rubygems:  "3.3.27"
+            bundler: none
+            gemfile: vanilla
+    runs-on: ubuntu-20.04
+    continue-on-error: ${{ matrix.experimental || endsWith(matrix.ruby, 'head') }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup Ruby & RubyGems
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "${{ matrix.ruby }}"
+          rubygems: "${{ matrix.rubygems }}"
+          bundler: "${{ matrix.bundler }}"
+          bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+      - name: Run tests
+        run: bundle exec rake test
diff --git a/.tool-versions b/.tool-versions
new file mode 100644
index 0000000..59511e1
--- /dev/null
+++ b/.tool-versions
@@ -0,0 +1 @@
+ruby 2.7.8
diff --git a/gemfiles/vanilla.gemfile b/gemfiles/vanilla.gemfile
new file mode 100644
index 0000000..b45c4e8
--- /dev/null
+++ b/gemfiles/vanilla.gemfile
@@ -0,0 +1,9 @@
+git_source(:github) { |repo_name| "https://github.com/#{repo_name}" }
+
+source "https://rubygems.org"
+
+# Root Gemfile is only for local development only. It is not loaded on CI.
+# On CI we only need the gemspecs' dependencies (including development dependencies).
+# Exceptions, if any, will be found in gemfiles/*.gemfile
+
+gemspec path: "../"
diff --git a/ruby-openid.gemspec b/ruby-openid.gemspec
index c7bb265..40e4859 100644
--- a/ruby-openid.gemspec
+++ b/ruby-openid.gemspec
@@ -23,4 +23,7 @@ Gem::Specification.new do |s|
   s.rdoc_options << '--main' << 'README.md'
 
   s.add_development_dependency 'minitest', '>= 5'
+  s.add_development_dependency 'rake', '>= 13'
+  s.add_development_dependency 'rexml', '~> 3.2'
+  s.add_development_dependency 'webrick', '~> 1.8'
 end