diff --git a/config/routes.rb b/config/routes.rb
index 4d075165..bd319530 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -25,9 +25,19 @@
 
     if Spree::Core::Engine.frontend_available?
       resources :users, only: [:edit, :update]
-      get '/checkout/registration' => 'checkout#registration', :as => :checkout_registration
-      put '/checkout/registration' => 'checkout#update_registration', :as => :update_checkout_registration
       resource :account, controller: 'users'
+
+      unless Spree::Auth::Engine.checkout_available?
+        get '/checkout/registration' => 'checkout#registration', :as => :checkout_registration
+        put '/checkout/registration' => 'checkout#update_registration', :as => :update_checkout_registration
+      end
+    end
+
+    if Spree::Auth::Engine.checkout_available?
+      namespace :checkout do
+        get :registration, to: 'orders#registration', as: :registration
+        put :registration, to: 'orders#update_registration', as: :update_registration
+      end
     end
 
     if Spree.respond_to?(:admin_path) && Spree::Core::Engine.backend_available?
diff --git a/lib/controllers/checkout/spree/auth/checkout/orders_controller_decorator.rb b/lib/controllers/checkout/spree/auth/checkout/orders_controller_decorator.rb
new file mode 100644
index 00000000..f45b01f6
--- /dev/null
+++ b/lib/controllers/checkout/spree/auth/checkout/orders_controller_decorator.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+module Spree
+  module Auth
+    module Checkout
+      #
+      # Adds methods to Spree Checkout Orders
+      module OrdersControllerDecorator
+        def self.prepended(base)
+          base.before_action :check_authorization
+          base.before_action :check_registration, except: %i[registration update_registration]
+        end
+
+        def registration
+          @user = Spree.user_class.new
+          @title = Spree.t(:registration)
+        end
+
+        def update_registration
+          if order_params[:email] =~ Devise.email_regexp && current_order.update_attribute(:email, order_params[:email])
+            redirect_to spree.checkout_state_path(:address)
+          else
+            flash[:error] = t(:email_is_invalid, scope: %i[errors messages])
+            @user = Spree.user_class.new
+            render 'registration', status: :unprocessable_entity
+          end
+        end
+
+        private
+
+        def order_params
+          params[:order].present? ? params.require(:order).permit(:email) : {}
+        end
+
+        def skip_state_validation?
+          %w[registration update_registration].include?(params[:action])
+        end
+
+        def check_authorization
+          authorize!(:edit, current_order, cookies.signed[:guest_token])
+        end
+
+        # Introduces a registration step whenever the +registration_step+ preference is true.
+        def check_registration
+          return unless Spree::Auth::Config[:registration_step]
+          return if spree_current_user || current_order.email
+
+          store_location
+          redirect_to spree.checkout_registration_path
+        end
+
+        Spree::Checkout::OrdersController.prepend(self) if ::Spree::Checkout::OrdersController.included_modules.exclude?(self)
+      end
+    end
+  end
+end
diff --git a/lib/controllers/checkout/spree/user_sessions_controller.rb b/lib/controllers/checkout/spree/user_sessions_controller.rb
new file mode 100644
index 00000000..690116b2
--- /dev/null
+++ b/lib/controllers/checkout/spree/user_sessions_controller.rb
@@ -0,0 +1,86 @@
+class Spree::UserSessionsController < Devise::SessionsController
+  helper 'spree/base'
+
+  include Spree::Core::ControllerHelpers::Auth
+  include Spree::Core::ControllerHelpers::Common
+  include Spree::Core::ControllerHelpers::Order
+  include Spree::Core::ControllerHelpers::Store
+
+  include SpreeI18n::ControllerLocaleHelper if defined?(SpreeI18n::ControllerLocaleHelper)
+
+  include Spree::Core::ControllerHelpers::Currency if defined?(Spree::Core::ControllerHelpers::Currency)
+  include Spree::Core::ControllerHelpers::Locale if defined?(Spree::Core::ControllerHelpers::Locale)
+
+  include Spree::LocaleUrls if defined?(Spree::LocaleUrls)
+
+  helper 'spree/locale' if defined?(Spree::LocaleHelper)
+  helper 'spree/currency' if defined?(Spree::CurrencyHelper)
+  helper 'spree/store' if defined?(Spree::StoreHelper)
+
+  before_action :set_current_order
+
+  def create
+    authenticate_spree_user!
+
+    if spree_user_signed_in?
+      respond_to do |format|
+        format.html {
+          flash[:success] = Spree.t(:logged_in_successfully)
+          redirect_back_or_default(after_sign_in_redirect(spree_current_user))
+        }
+        format.js {
+          render json: { user: spree_current_user,
+                           ship_address: spree_current_user.ship_address,
+                           bill_address: spree_current_user.bill_address }.to_json
+        }
+      end
+    else
+      respond_to do |format|
+        format.html {
+          flash.now[:error] = t('devise.failure.invalid')
+          render :new, status: :unprocessable_entity
+        }
+        format.js {
+          render json: { error: t('devise.failure.invalid') }, status: :unprocessable_entity
+        }
+      end
+    end
+  end
+
+  protected
+
+  def translation_scope
+    'devise.user_sessions'
+  end
+
+  private
+
+  def accurate_title
+    Spree.t(:login)
+  end
+
+  def redirect_back_or_default(default)
+    redirect_to(session["spree_user_return_to"] || default)
+    session["spree_user_return_to"] = nil
+  end
+
+  def after_sign_in_redirect(resource_or_scope)
+    stored_location_for(resource_or_scope) || spree.account_path
+  end
+
+  def respond_to_on_destroy
+    # We actually need to hardcode this as Rails default responder doesn't
+    # support returning empty response on GET request
+    respond_to do |format|
+      format.all { head :no_content }
+      format.any(*navigational_formats) { redirect_to after_sign_out_redirect(resource_name) }
+    end
+  end
+
+  def after_sign_out_redirect(resource_or_scope)
+    scope = Devise::Mapping.find_scope!(resource_or_scope)
+    router_name = Devise.mappings[scope].router_name
+    context = router_name ? send(router_name) : self
+    context.respond_to?(:login_path) ? context.login_path(locale_param) : spree.root_path
+  end
+end
diff --git a/lib/spree/auth/engine.rb b/lib/spree/auth/engine.rb
index 01ed4480..081186af 100644
--- a/lib/spree/auth/engine.rb
+++ b/lib/spree/auth/engine.rb
@@ -30,6 +30,11 @@ def self.activate
         Dir.glob(File.join(File.dirname(__FILE__), '../../app/**/*_decorator*.rb')) do |c|
           Rails.configuration.cache_classes ? require(c) : load(c)
         end
+        if Spree::Auth::Engine.checkout_available?
+          Dir.glob(File.join(File.dirname(__FILE__), "../../controllers/checkout/**/*_decorator*.rb")) do |c|
+            Rails.configuration.cache_classes ? require(c) : load(c)
+          end
+        end
         if Spree::Auth::Engine.backend_available?
           Dir.glob(File.join(File.dirname(__FILE__), "../../controllers/backend/*/*/*_decorator*.rb")) do |c|
             Rails.configuration.cache_classes ? require(c) : load(c)
@@ -45,11 +50,12 @@ def self.activate
             Rails.configuration.cache_classes ? require(c) : load(c)
           end
         end
+
         ApplicationController.send :include, Spree::AuthenticationHelpers
       end
 
-      def self.api_available?
-        @@api_available ||= ::Rails::Engine.subclasses.map(&:instance).map{ |e| e.class.to_s }.include?('Spree::Api::Engine')
+      def self.checkout_available?
+        @@checkout_available ||= ::Rails::Engine.subclasses.map(&:instance).map{ |e| e.class.to_s }.include?('Spree::Checkout::Engine')
       end
 
       def self.backend_available?
@@ -68,6 +74,11 @@ def self.emails_available?
         @@emails_available ||= ::Rails::Engine.subclasses.map(&:instance).map{ |e| e.class.to_s }.include?('Spree::Emails::Engine')
       end
 
+      if checkout_available?
+        paths["app/controllers"] << "lib/controllers/checkout"
+        paths["app/views"] << "lib/views/checkout"
+      end
+
       if backend_available?
         paths["app/controllers"] << "lib/controllers/backend"
         paths["app/views"] << "lib/views/backend"