diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 00000000..a8d3b334
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,41 @@
+name: Ruby CI
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: true
+      matrix:
+        ruby-version:
+          - 3.0.0
+          - 2.7.2
+          - 2.6.6
+          - 2.5.8
+        experimental: [false]
+        include:
+          - ruby-version: head
+            experimental: true
+
+    continue-on-error: ${{ matrix.experimental }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Ruby ${{ matrix.ruby-version }}
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby-version }}
+          bundler-cache: true
+      - name: Install dependencies
+        run: |
+          bundle config set --local path '../../vendor/bundle'
+          bundle install
+      - name: Run tests
+        run: bundle exec rake
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 00000000..b8a5c0ed
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,22 @@
+name: Linting
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 3.0
+          bundler-cache: true
+      - run: bundle install
+      - name: Rubocop
+        run: bundle exec rake rubocop
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 00000000..81748ee8
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,4 @@
+inherit_gem:
+  rubocop-standard:
+    - config/default.yml
+    - config/minitest.yml
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index ff321ccd..00000000
--- a/.travis.yml
+++ /dev/null
@@ -1,43 +0,0 @@
-language: ruby
-cache: bundler
-bundler_args: --path ../../vendor/bundle
-
-addons:
-  apt:
-    sources:
-      - libicu-dev
-      - kalakris-cmake
-    packages:
-      - cmake
-
-script: bundle exec rake
-
-gemfile:
-  - gemfiles/rails_6.gemfile
-  - gemfiles/rails_5.gemfile
-  - gemfiles/rails_4.gemfile
-  - gemfiles/rails_3.gemfile
-
-rvm:
-  - 2.4.6
-  - 2.3.8
-  - 2.5.7
-  - ruby-head
-
-matrix:
-  fast_finish: true
-  allow_failures:
-    - rvm: ruby-head
-  exclude:
-    - gemfile: gemfiles/rails_6.gemfile
-      rvm: 2.4.6
-    - gemfile: gemfiles/rails_6.gemfile
-      rvm: 2.3.8
-    - gemfile: gemfiles/rails_4.gemfile
-      rvm: 2.5.7
-    - gemfile: gemfiles/rails_4.gemfile
-      rvm: 2.4.6
-    - gemfile: gemfiles/rails_3.gemfile
-      rvm: 2.5.7
-    - gemfile: gemfiles/rails_3.gemfile
-      rvm: 2.4.6
diff --git a/Appraisals b/Appraisals
deleted file mode 100644
index 6037fd68..00000000
--- a/Appraisals
+++ /dev/null
@@ -1,19 +0,0 @@
-# frozen_string_literal: true
-
-appraise 'rails-3' do
-  gem 'rack', '< 2'
-  gem 'rails', '3.2.22.2'
-end
-
-appraise 'rails-4' do
-  gem 'rack', '< 2'
-  gem 'rails', '~> 4.2.6'
-end
-
-appraise 'rails-5' do
-  gem 'rails', '~> 5.0.0'
-end
-
-appraise 'rails-6' do
-  gem 'rails', '~> 6.0.0'
-end
diff --git a/Gemfile b/Gemfile
index adc923bd..d4890b59 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,8 +5,15 @@ source 'https://rubygems.org'
 # Specify your gem's dependencies in html-pipeline.gemspec
 gemspec
 
+group :development, :test do
+  gem 'awesome_print'
+
+  gem 'rubocop'
+  gem 'rubocop-performance'
+  gem 'rubocop-standard'
+end
+
 group :development do
-  gem 'appraisal'
   gem 'bundler'
   gem 'rake'
 end
@@ -16,11 +23,11 @@ group :test do
   gem 'email_reply_parser', '~> 0.5', require: false
   gem 'gemoji', '~> 2.0', require: false
   gem 'minitest'
-  gem 'RedCloth',           '~> 4.2.9', require: false
-  gem 'rinku',              '~> 1.7',   require: false
-  gem 'sanitize',           '~> 4.6', require: false
+  gem 'RedCloth',           '~> 4.3', require: false
+  gem 'rinku',              '~> 1.7', require: false
+  gem 'sanitize',           '~> 5.2', require: false
 
   gem 'escape_utils', '~> 1.0', require: false
-  gem 'rouge', '~> 3.1', require: false
   gem 'minitest-focus', '~> 1.1'
+  gem 'rouge', '~> 3.1', require: false
 end
diff --git a/Rakefile b/Rakefile
index f26f9adc..cc4508a3 100755
--- a/Rakefile
+++ b/Rakefile
@@ -15,3 +15,7 @@ Rake::TestTask.new do |t|
 end
 
 task default: :test
+
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new(:rubocop)
diff --git a/gemfiles/rails_3.gemfile b/gemfiles/rails_3.gemfile
deleted file mode 100644
index d3497431..00000000
--- a/gemfiles/rails_3.gemfile
+++ /dev/null
@@ -1,27 +0,0 @@
-# This file was generated by Appraisal
-
-source "https://rubygems.org"
-
-gem "rack", "< 2"
-gem "rails", "3.2.22.2"
-
-group :development do
-  gem "appraisal"
-  gem "bundler"
-  gem "rake"
-end
-
-group :test do
-  gem "commonmarker", "~> 0.16", require: false
-  gem "email_reply_parser", "~> 0.5", require: false
-  gem "gemoji", "~> 2.0", require: false
-  gem "minitest"
-  gem "RedCloth", "~> 4.2.9", require: false
-  gem "rinku", "~> 1.7", require: false
-  gem "sanitize", "~> 4.6", require: false
-  gem "escape_utils", "~> 1.0", require: false
-  gem "rouge", "~> 3.1", require: false
-  gem "minitest-focus", "~> 1.1"
-end
-
-gemspec path: "../"
diff --git a/gemfiles/rails_4.gemfile b/gemfiles/rails_4.gemfile
deleted file mode 100644
index a00d20ad..00000000
--- a/gemfiles/rails_4.gemfile
+++ /dev/null
@@ -1,27 +0,0 @@
-# This file was generated by Appraisal
-
-source "https://rubygems.org"
-
-gem "rack", "< 2"
-gem "rails", "~> 4.2.6"
-
-group :development do
-  gem "appraisal"
-  gem "bundler"
-  gem "rake"
-end
-
-group :test do
-  gem "commonmarker", "~> 0.16", require: false
-  gem "email_reply_parser", "~> 0.5", require: false
-  gem "gemoji", "~> 2.0", require: false
-  gem "minitest"
-  gem "RedCloth", "~> 4.2.9", require: false
-  gem "rinku", "~> 1.7", require: false
-  gem "sanitize", "~> 4.6", require: false
-  gem "escape_utils", "~> 1.0", require: false
-  gem "rouge", "~> 3.1", require: false
-  gem "minitest-focus", "~> 1.1"
-end
-
-gemspec path: "../"
diff --git a/gemfiles/rails_5.gemfile b/gemfiles/rails_5.gemfile
deleted file mode 100644
index 1f64a4f9..00000000
--- a/gemfiles/rails_5.gemfile
+++ /dev/null
@@ -1,26 +0,0 @@
-# This file was generated by Appraisal
-
-source "https://rubygems.org"
-
-gem "rails", "~> 5.0.0"
-
-group :development do
-  gem "appraisal"
-  gem "bundler"
-  gem "rake"
-end
-
-group :test do
-  gem "commonmarker", "~> 0.16", require: false
-  gem "email_reply_parser", "~> 0.5", require: false
-  gem "gemoji", "~> 2.0", require: false
-  gem "minitest"
-  gem "RedCloth", "~> 4.2.9", require: false
-  gem "rinku", "~> 1.7", require: false
-  gem "sanitize", "~> 4.6", require: false
-  gem "escape_utils", "~> 1.0", require: false
-  gem "rouge", "~> 3.1", require: false
-  gem "minitest-focus", "~> 1.1"
-end
-
-gemspec path: "../"
diff --git a/gemfiles/rails_6.gemfile b/gemfiles/rails_6.gemfile
deleted file mode 100644
index 134e8425..00000000
--- a/gemfiles/rails_6.gemfile
+++ /dev/null
@@ -1,26 +0,0 @@
-# This file was generated by Appraisal
-
-source "https://rubygems.org"
-
-gem "rails", "~> 6.0.0"
-
-group :development do
-  gem "appraisal"
-  gem "bundler"
-  gem "rake"
-end
-
-group :test do
-  gem "commonmarker", "~> 0.16", require: false
-  gem "email_reply_parser", "~> 0.5", require: false
-  gem "gemoji", "~> 2.0", require: false
-  gem "minitest"
-  gem "RedCloth", "~> 4.2.9", require: false
-  gem "rinku", "~> 1.7", require: false
-  gem "sanitize", "~> 4.6", require: false
-  gem "escape_utils", "~> 1.0", require: false
-  gem "rouge", "~> 3.1", require: false
-  gem "minitest-focus", "~> 1.1"
-end
-
-gemspec path: "../"
diff --git a/html-pipeline.gemspec b/html-pipeline.gemspec
index ec88cfe2..cf8dccb6 100644
--- a/html-pipeline.gemspec
+++ b/html-pipeline.gemspec
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require File.expand_path('../lib/html/pipeline/version', __FILE__)
+require File.expand_path('lib/html/pipeline/version', __dir__)
 
 Gem::Specification.new do |gem|
   gem.name          = 'html-pipeline'
@@ -8,22 +8,23 @@ Gem::Specification.new do |gem|
   gem.license       = 'MIT'
   gem.authors       = ['Ryan Tomayko', 'Jerry Cheung', 'Garen J. Torikian']
   gem.email         = ['ryan@github.com', 'jerry@github.com', 'gjtorikian@gmail.com']
-  gem.description   = 'GitHub HTML processing filters and utilities'
+  gem.description   = 'HTML processing filters and utilities'
   gem.summary       = 'Helpers for processing content through a chain of filters'
   gem.homepage      = 'https://github.com/jch/html-pipeline'
 
   gem.files         = `git ls-files -z`.split("\x0").reject { |f| f =~ %r{^(test|gemfiles|script)/} }
   gem.require_paths = ['lib']
 
-  gem.add_dependency 'activesupport', '>= 2'
-  gem.add_dependency 'nokogiri', '>= 1.4'
+  gem.required_ruby_version = ['>= 2.5.8', '< 4.0']
 
-  gem.post_install_message = <<msg
--------------------------------------------------
-Thank you for installing html-pipeline!
-You must bundle Filter gem dependencies.
-See html-pipeline README.md for more details.
-https://github.com/jch/html-pipeline#dependencies
--------------------------------------------------
-msg
+  gem.add_dependency 'nokogiri', '~> 1.11'
+
+  gem.post_install_message = <<~MSG
+    -------------------------------------------------
+    Thank you for installing html-pipeline!
+    You must bundle Filter gem dependencies.
+    See html-pipeline README.md for more details.
+    https://github.com/jch/html-pipeline#dependencies
+    -------------------------------------------------
+  MSG
 end
diff --git a/lib/html/pipeline.rb b/lib/html/pipeline.rb
index 8f5cf8db..f1277b46 100644
--- a/lib/html/pipeline.rb
+++ b/lib/html/pipeline.rb
@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 require 'nokogiri'
-require 'active_support/xml_mini/nokogiri' # convert Documents to hashes
 
 module HTML
   # GitHub HTML processing filters and utilities. This module includes a small
diff --git a/lib/html/pipeline/emoji_filter.rb b/lib/html/pipeline/emoji_filter.rb
index d22bb479..161b4093 100644
--- a/lib/html/pipeline/emoji_filter.rb
+++ b/lib/html/pipeline/emoji_filter.rb
@@ -68,12 +68,15 @@ def asset_path(name)
 
       # Build an emoji image tag
       def emoji_image_tag(name)
-        require 'active_support/core_ext/hash/indifferent_access'
         html_attrs =
-          default_img_attrs(name)
-          .merge!((context[:img_attrs] || {}).with_indifferent_access)
-          .map { |attr, value| !value.nil? && %(#{attr}="#{value.respond_to?(:call) && value.call(name) || value}") }
-          .reject(&:blank?).join(' '.freeze)
+          default_img_attrs(name).transform_keys(&:to_sym)
+          .merge!(context[:img_attrs] || {}).transform_keys(&:to_sym)
+          .each_with_object([]) do |(attr, value), arr|
+            next if value.nil?
+
+            value = value.respond_to?(:call) && value.call(name) || value
+            arr << %(#{attr}="#{value}")
+          end.compact.join(' '.freeze)
 
         "<img #{html_attrs}>"
       end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index ddb78e80..530e272d 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -6,14 +6,12 @@
 require 'minitest/pride'
 require 'minitest/focus'
 
-require 'active_support/core_ext/string'
-
 module TestHelpers
   # Asserts that two html fragments are equivalent. Attribute order
   # will be ignored.
   def assert_equal_html(expected, actual)
-    assert_equal Nokogiri::HTML::DocumentFragment.parse(expected).to_hash,
-                 Nokogiri::HTML::DocumentFragment.parse(actual).to_hash
+    assert_equal Nokogiri::HTML::DocumentFragment.parse(expected).to_h,
+                 Nokogiri::HTML::DocumentFragment.parse(actual).to_h
   end
 end