diff --git a/.buildkite/pipeline.yml b/.buildkite/pipeline.yml
index fb64720c2..d7b614666 100644
--- a/.buildkite/pipeline.yml
+++ b/.buildkite/pipeline.yml
@@ -5,7 +5,7 @@ steps:
     env:
       RUBY_VERSION: "{{ matrix.ruby }}"
       TEST_SUITE: "{{ matrix.suite }}"
-      STACK_VERSION: 8.16.0-SNAPSHOT
+      STACK_VERSION: 9.0.0-SNAPSHOT
       TRANSPORT_VERSION: "{{ matrix.transport }}"
       RUBY_SOURCE: "{{ matrix.ruby_source }}"
       QUIET: false
@@ -67,7 +67,7 @@ steps:
       provider: "gcp"
     env:
       RUBY_VERSION: "3.3"
-      STACK_VERSION: 8.16.0-SNAPSHOT
+      STACK_VERSION: 9.0.0-SNAPSHOT
       ES_YAML_TESTS_BRANCH: main
       TRANSPORT_VERSION: "8.3"
       RUBY_SOURCE: "ruby"
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 766ef5fe2..6b08d2071 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -26,7 +26,7 @@ jobs:
         sudo sysctl -w vm.max_map_count=262144
     - uses: elastic/elastic-github-actions/elasticsearch@master
       with:
-        stack-version: 8.16.0-SNAPSHOT
+        stack-version: 9.0.0-SNAPSHOT
         security-enabled: false
     - uses: ruby/setup-ruby@v1
       with:
@@ -40,4 +40,4 @@ jobs:
     - name: elasticsearch
       run: cd elasticsearch && bundle exec rake test:all
     - name: elasticsearch-api
-      run: rake es:download_artifacts[8.16.0-SNAPSHOT] && cd elasticsearch-api && bundle exec rake test:spec test:platinum:unit
+      run: rake es:download_artifacts[9.0.0-SNAPSHOT] && cd elasticsearch-api && bundle exec rake test:spec test:platinum:unit
diff --git a/.github/workflows/otel.yml b/.github/workflows/otel.yml
index 56d6b9a5f..238305e75 100644
--- a/.github/workflows/otel.yml
+++ b/.github/workflows/otel.yml
@@ -28,7 +28,7 @@ jobs:
           sudo sysctl -w vm.max_map_count=262144
       - uses: elastic/elastic-github-actions/elasticsearch@master
         with:
-          stack-version: 8.16.0-SNAPSHOT
+          stack-version: 9.0.0-SNAPSHOT
           security-enabled: false
       - uses: ruby/setup-ruby@v1
         with:
@@ -42,4 +42,4 @@ jobs:
       - name: elasticsearch
         run: cd elasticsearch && bundle exec rake test:all
       - name: elasticsearch-api
-        run: rake es:download_artifacts[8.16.0-SNAPSHOT] && cd elasticsearch-api && bundle exec rake test:spec test:platinum:unit
+        run: rake es:download_artifacts[9.0.0-SNAPSHOT] && cd elasticsearch-api && bundle exec rake test:spec test:platinum:unit
diff --git a/elasticsearch-api/elasticsearch-api.gemspec b/elasticsearch-api/elasticsearch-api.gemspec
index a458ed60d..f2149ebda 100644
--- a/elasticsearch-api/elasticsearch-api.gemspec
+++ b/elasticsearch-api/elasticsearch-api.gemspec
@@ -59,15 +59,10 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'yard'
 
   # Gems for testing integrations
-  s.add_development_dependency 'jsonify'
+  s.add_development_dependency 'activesupport'
   s.add_development_dependency 'hashie'
-  # Temporary support for Ruby 2.6, since it's EOL March 2022:
-  if RUBY_VERSION < '2.7.0'
-    s.add_development_dependency 'jbuilder', '< 7.0.0'
-  else
-    s.add_development_dependency 'activesupport'
-    s.add_development_dependency 'jbuilder'
-  end
+  s.add_development_dependency 'jbuilder'
+  s.add_development_dependency 'jsonify'
 
   s.add_development_dependency 'cane'
   s.add_development_dependency 'escape_utils' unless defined? JRUBY_VERSION
diff --git a/elasticsearch-api/lib/elasticsearch/api/version.rb b/elasticsearch-api/lib/elasticsearch/api/version.rb
index e43ee587d..a8d55bf70 100644
--- a/elasticsearch-api/lib/elasticsearch/api/version.rb
+++ b/elasticsearch-api/lib/elasticsearch/api/version.rb
@@ -17,6 +17,6 @@
 
 module Elasticsearch
   module API
-    VERSION = '8.14.0'.freeze
+    VERSION = '9.0.0'.freeze
   end
 end
diff --git a/elasticsearch-api/spec/elasticsearch/api/perform_request_spec.rb b/elasticsearch-api/spec/elasticsearch/api/perform_request_spec.rb
index a075ce257..44b3fa288 100644
--- a/elasticsearch-api/spec/elasticsearch/api/perform_request_spec.rb
+++ b/elasticsearch-api/spec/elasticsearch/api/perform_request_spec.rb
@@ -23,7 +23,7 @@
 describe 'Perform request args' do
   Elasticsearch::API::FilesHelper.files.each do |filepath|
     spec = Elasticsearch::API::EndpointSpec.new(filepath)
-    next if spec.module_namespace.flatten.first == '_internal'
+    next if spec.module_namespace.flatten.first == '_internal' || spec.visibility != 'public'
 
     # These are the path parts defined by the user in the method argument
     defined_path_parts = spec.path_params.inject({}) do |params, part|
diff --git a/elasticsearch-api/utils/thor/endpoint_spec.rb b/elasticsearch-api/utils/thor/endpoint_spec.rb
index 30a06a556..a309cbb9e 100644
--- a/elasticsearch-api/utils/thor/endpoint_spec.rb
+++ b/elasticsearch-api/utils/thor/endpoint_spec.rb
@@ -24,6 +24,23 @@ module API
     class EndpointSpec
       include EndpointSpecifics
 
+      # These APIs are private, but were added in 8.x since the generator didn't consider
+      # visibility. They will be removed in 9.x since we're using a different generator that
+      # considers visibility. But new private APIs code won't be generated for the client.
+      EXCLUDED_8X = [
+        'autoscaling.delete_autoscaling_policy', 'autoscaling.get_autoscaling_capacity',
+        'autoscaling.get_autoscaling_policy', 'autoscaling.put_autoscaling_policy', 'capabilities',
+        'connector.secret_delete', 'connector.secret_get', 'connector.secret_post',
+        'connector.secret_put', 'fleet.delete_secret', 'fleet.get_secret', 'fleet.post_secret',
+        'ml.validate', 'ml.validate_detector', 'monitoring.bulk', 'profiling.flamegraph',
+        'profiling.stacktraces', 'profiling.status', 'profiling.topn_functions',
+        'security.activate_user_profile', 'security.disable_user_profile',
+        'security.enable_user_profile', 'security.get_user_profile',
+        'security.has_privileges_user_profile', 'security.suggest_user_profiles',
+        'security.update_user_profile_data', 'shutdown.delete_node', 'shutdown.get_node',
+        'shutdown.put_node'
+      ].freeze
+
       def initialize(filepath)
         @path = Pathname(filepath)
         json = MultiJson.load(File.read(@path))
@@ -31,14 +48,14 @@ def initialize(filepath)
         @endpoint_name = json.keys.first
 
         full_namespace = parse_full_namespace
-        @namespace_depth = full_namespace.size > 0 ? full_namespace.size - 1 : 0
+        @namespace_depth = full_namespace.size.positive? ? full_namespace.size - 1 : 0
         @module_namespace = full_namespace[0, @namespace_depth]
         @method_name = full_namespace.last
 
         @path_parts = parse_endpoint_parts(@spec)
         @params = @spec['params'] || {}
         @paths = @spec['url']['paths'].map { |b| b['path'] } if @spec['url']
-        @path_params   = path_variables.flatten.uniq.collect(&:to_sym)
+        @path_params = path_variables.flatten.uniq.collect(&:to_sym)
         @http_method = parse_http_method(@spec)
         @deprecation_note = @spec['url']['paths'].last&.[]('deprecated')
         @http_path        = parse_http_path(@paths)
@@ -71,6 +88,16 @@ def stability
         @spec['stability']
       end
 
+      def visibility
+        @spec['visibility']
+      end
+
+      def skippable?
+        return true if module_namespace.flatten.first == '_internal'
+
+        visibility != 'public' && !EXCLUDED_8X.include?(endpoint_name)
+      end
+
       # Function that adds the listified h param code
       def specific_params
         super(@module_namespace.first, @method_name)
diff --git a/elasticsearch-api/utils/thor/generate_source.rb b/elasticsearch-api/utils/thor/generate_source.rb
index df60b0004..acdf8bb41 100644
--- a/elasticsearch-api/utils/thor/generate_source.rb
+++ b/elasticsearch-api/utils/thor/generate_source.rb
@@ -68,7 +68,7 @@ def generate_source
           @spec = EndpointSpec.new(filepath)
           say_status 'json', @spec.path, :yellow
           # Don't generate code for internal APIs:
-          next if @spec.module_namespace.flatten.first == '_internal'
+          next if @spec.skippable?
 
           path_to_file = output.join(@spec.module_namespace.join('/')).join("#{@spec.method_name}.rb")
           dir = output.join(@spec.module_namespace.join('/'))
diff --git a/elasticsearch/elasticsearch.gemspec b/elasticsearch/elasticsearch.gemspec
index d7dbdc900..c30c83e26 100644
--- a/elasticsearch/elasticsearch.gemspec
+++ b/elasticsearch/elasticsearch.gemspec
@@ -46,7 +46,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = '>= 2.5'
 
   s.add_dependency 'elastic-transport', '~> 8.3'
-  s.add_dependency 'elasticsearch-api', '8.14.0'
+  s.add_dependency 'elasticsearch-api', '9.0.0'
 
   s.add_development_dependency 'base64'
   s.add_development_dependency 'bundler'
diff --git a/elasticsearch/lib/elasticsearch/version.rb b/elasticsearch/lib/elasticsearch/version.rb
index 099a40a40..33758a094 100644
--- a/elasticsearch/lib/elasticsearch/version.rb
+++ b/elasticsearch/lib/elasticsearch/version.rb
@@ -16,5 +16,5 @@
 # under the License.
 
 module Elasticsearch
-  VERSION = '8.14.0'.freeze
+  VERSION = '9.0.0'.freeze
 end