diff --git a/Gemfile b/Gemfile
index 531cad50a..b248030e9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,6 +2,7 @@ source 'https://rubygems.org'
 
 # core
 gem 'active_interaction', '~> 3.8'
+gem 'apipie-rails', '~> 0.5.18'
 gem 'bootsnap', '>= 1.1.0', require: false
 gem 'iso8601', '0.12.1' # for dates and times
 gem 'rails', '~> 6.0'
@@ -78,7 +79,6 @@ gem 'wkhtmltopdf-binary', '~> 0.12.5.1'
 
 gem 'directo', github: 'internetee/directo', branch: 'master'
 
-
 group :development, :test do
   gem 'pry', '0.10.1'
   gem 'puma'
@@ -92,5 +92,3 @@ group :test do
   gem 'webdrivers'
   gem 'webmock'
 end
-
-gem "apipie-rails", "~> 0.5.18"
diff --git a/app/controllers/repp/v1/accounts_controller.rb b/app/controllers/repp/v1/accounts_controller.rb
index 00f70ea63..7397b274d 100644
--- a/app/controllers/repp/v1/accounts_controller.rb
+++ b/app/controllers/repp/v1/accounts_controller.rb
@@ -1,7 +1,6 @@
 module Repp
   module V1
     class AccountsController < BaseController
-
       api :GET, '/repp/v1/accounts/balance'
       desc "Get account's balance"
       def balance
diff --git a/app/controllers/repp/v1/base_controller.rb b/app/controllers/repp/v1/base_controller.rb
index a4e613786..339d03311 100644
--- a/app/controllers/repp/v1/base_controller.rb
+++ b/app/controllers/repp/v1/base_controller.rb
@@ -9,7 +9,8 @@ module Repp
 
       before_action :set_paper_trail_whodunnit
 
-      rescue_from ActionController::ParameterMissing, Apipie::ParamInvalid, Apipie::ParamMissing do |exception|
+      rescue_from ActionController::ParameterMissing, Apipie::ParamInvalid,
+                  Apipie::ParamMissing do |exception|
         render json: { code: 2003, message: exception }, status: :bad_request
       end
 
diff --git a/app/controllers/repp/v1/domains/contacts_controller.rb b/app/controllers/repp/v1/domains/contacts_controller.rb
index 1705e7cc0..86cbf0acf 100644
--- a/app/controllers/repp/v1/domains/contacts_controller.rb
+++ b/app/controllers/repp/v1/domains/contacts_controller.rb
@@ -6,6 +6,13 @@ module Repp
         before_action :set_new_contact, only: [:update]
         before_action :set_domain, only: %i[index create destroy]
 
+        def_param_group :contacts_apidoc do
+          param :contacts, Array, required: true, desc: 'Array of new linked contacts' do
+            param :code, String, required: true, desc: 'Contact code'
+            param :type, String, required: true, desc: 'Role of contact (admin/tech)'
+          end
+        end
+
         api :GET, '/repp/v1/domains/:domain_name/contacts'
         desc "View domain's admin and tech contacts"
         def index
@@ -17,11 +24,8 @@ module Repp
         end
 
         api :POST, '/repp/v1/domains/:domain_name/contacts'
-        desc "Link new contact(s) to domain"
-        param :contacts, Array, required: true, desc: 'Array of new linked contacts' do
-          param :code, String, required: true, desc: 'Contact code'
-          param :type, String, required: true, desc: 'Role of contact (admin/tech)'
-        end
+        desc 'Link new contact(s) to domain'
+        param_group :contacts_apidoc
         def create
           contact_create_params[:contacts].each { |c| c[:action] = 'add' }
           action = Actions::DomainUpdate.new(@domain, contact_create_params, current_user)
@@ -35,11 +39,8 @@ module Repp
         end
 
         api :DELETE, '/repp/v1/domains/:domain_name/contacts'
-        desc "Remove contact(s) from domain"
-        param :contacts, Array, required: true, desc: 'Array of new linked contacts' do
-          param :code, String, required: true, desc: 'Contact code'
-          param :type, String, required: true, desc: 'Role of contact (admin/tech)'
-        end
+        desc 'Remove contact(s) from domain'
+        param_group :contacts_apidoc
         def destroy
           contact_create_params[:contacts].each { |c| c[:action] = 'rem' }
           action = Actions::DomainUpdate.new(@domain, contact_create_params, current_user)
diff --git a/app/controllers/repp/v1/domains/dnssec_controller.rb b/app/controllers/repp/v1/domains/dnssec_controller.rb
index 717210091..ec3a3bd7f 100644
--- a/app/controllers/repp/v1/domains/dnssec_controller.rb
+++ b/app/controllers/repp/v1/domains/dnssec_controller.rb
@@ -4,6 +4,13 @@ module Repp
       class DnssecController < BaseController
         before_action :set_domain, only: %i[index create destroy]
 
+        def_param_group :dns_keys_apidoc do
+          param :flags, String, required: true, desc: '256 (KSK) or 257 (ZSK)'
+          param :protocol, String, required: true, desc: 'Key protocol (3)'
+          param :alg, String, required: true, desc: 'DNSSEC key algorithm (3,5,6,7,8,10,13,14)'
+          param :public_key, String, required: true, desc: 'DNSSEC public key'
+        end
+
         api :GET, '/repp/v1/domains/:domain_name/dnssec'
         desc "View specific domain's DNSSEC keys"
         def index
@@ -15,10 +22,7 @@ module Repp
         api :POST, '/repp/v1/domains/:domain_name/dnssec'
         desc 'Create a new DNSSEC key(s) for domain'
         param :dns_keys, Array, required: true, desc: 'Array of new DNSSEC keys' do
-          param :flags, String, required: true, desc: '256 (KSK) or 257 (ZSK)'
-          param :protocol, String, required: true, desc: 'Key protocol (3)'
-          param :alg, String, required: true, desc: 'DNSSEC key algorithm (3,5,6,7,8,10,13,14)'
-          param :public_key, String, required: true, desc: 'DNSSEC public key'
+          param_group :dns_keys_apidoc, DnssecController
         end
         def create
           dnssec_params[:dnssec][:dns_keys].each { |n| n[:action] = 'add' }
@@ -33,11 +37,8 @@ module Repp
         end
 
         api :DELETE, 'repp/v1/domains/:domain_name/dnssec'
-        param :dns_keys, Array, required: true, desc: 'Array of removable DNSSEC keys' do
-          param :flags, String, required: true, desc: '256 (KSK) or 257 (ZSK)'
-          param :protocol, String, required: true, desc: 'Key protocol (3)'
-          param :alg, String, required: true, desc: 'DNSSEC key algorithm (3,5,6,7,8,10,13,14)'
-          param :public_key, String, required: true, desc: 'DNSSEC public key'
+        param :dns_keys, Array, required: true, desc: 'Array of new DNSSEC keys' do
+          param_group :dns_keys_apidoc, DnssecController
         end
         def destroy
           dnssec_params[:dnssec][:dns_keys].each { |n| n[:action] = 'rem' }
diff --git a/app/controllers/repp/v1/domains/statuses_controller.rb b/app/controllers/repp/v1/domains/statuses_controller.rb
index 413544232..1b1d47477 100644
--- a/app/controllers/repp/v1/domains/statuses_controller.rb
+++ b/app/controllers/repp/v1/domains/statuses_controller.rb
@@ -4,14 +4,14 @@ module Repp
       class StatusesController < BaseController
         before_action :set_domain, only: %i[update destroy]
         before_action :verify_status
-        before_action :verify_status_removal, only: [:destroy]
-        before_action :verify_status_create, only: [:update]
 
         api :DELETE, '/repp/v1/domains/:domain_name/statuses/:status'
         desc 'Remove status from specific domain'
         param :domain_name, String, required: true, desc: 'Domain name'
         param :status, String, required: true, desc: 'Status to be removed'
         def destroy
+          return editing_failed unless @domain.statuses.include?(params[:id])
+
           @domain.statuses = @domain.statuses.delete(params[:id])
           if @domain.save
             render_success
@@ -25,8 +25,12 @@ module Repp
         param :domain_name, String, required: true, desc: 'Domain name'
         param :status, String, required: true, desc: 'Status to be added'
         def update
+          return editing_failed if @domain.statuses.include?(params[:id])
+
           @domain.statuses = @domain.statuses << params[:id]
+          # rubocop:disable Style/AndOr
           handle_errors(@domain) and return unless @domain.save
+          # rubocop:enable Style/AndOr
 
           render_success(data: { domain: @domain.name, status: params[:id] })
         end
@@ -39,23 +43,16 @@ module Repp
 
           return if allowed_statuses.include?(stat)
 
-          @domain.add_epp_error('2306', nil, nil, "#{I18n.t(:client_side_status_editing_error)}: status #{stat}")
+          @domain.add_epp_error('2306', nil, nil,
+                                "#{I18n.t(:client_side_status_editing_error)}: status #{stat}")
           handle_errors(@domain)
         end
 
-        def verify_status_removal
+        def editing_failed
           stat = params[:id]
-          return if @domain.statuses.include?(stat)
 
-          @domain.add_epp_error('2306', nil, nil, "#{I18n.t(:client_side_status_editing_error)}: status #{stat}")
-          handle_errors(@domain)
-        end
-
-        def verify_status_create
-          stat = params[:id]
-          return unless @domain.statuses.include?(stat)
-
-          @domain.add_epp_error('2306', nil, nil, "#{I18n.t(:client_side_status_editing_error)}: status #{stat}")
+          @domain.add_epp_error('2306', nil, nil,
+                                "#{I18n.t(:client_side_status_editing_error)}: status #{stat}")
           handle_errors(@domain)
         end
       end
diff --git a/app/controllers/repp/v1/domains/transfers_controller.rb b/app/controllers/repp/v1/domains/transfers_controller.rb
index be1f754c2..2594205d6 100644
--- a/app/controllers/repp/v1/domains/transfers_controller.rb
+++ b/app/controllers/repp/v1/domains/transfers_controller.rb
@@ -24,8 +24,9 @@ module Repp
         private
 
         def set_domain
+          domain_id = transfer_params[:domain_id]
           h = {}
-          h[transfer_params[:domain_id].match?(/\A[0-9]+\z/) ? :id : :name] = transfer_params[:domain_id]
+          h[domain_id.match?(/\A[0-9]+\z/) ? :id : :name] = domain_id
           @domain = Epp::Domain.find_by!(h)
         end
 
diff --git a/app/controllers/repp/v1/domains_controller.rb b/app/controllers/repp/v1/domains_controller.rb
index db1ea465d..8e77cd219 100644
--- a/app/controllers/repp/v1/domains_controller.rb
+++ b/app/controllers/repp/v1/domains_controller.rb
@@ -38,13 +38,12 @@ module Repp
           param :ipv4, Array, desc: 'Array of IPv4 addresses'
           param :ipv6, Array, desc: 'Array of IPv4 addresses'
         end
-        param :admin_domain_contacts_attributes, Array, required: false, desc: 'Admin domain contacts codes'
-        param :tech_domain_contacts_attributes, Array, required: false, desc: 'Tech domain contacts codes'
+        param :admin_domain_contacts_attributes, Array, required: false,
+                                                        desc: 'Admin domain contacts codes'
+        param :tech_domain_contacts_attributes, Array, required: false,
+                                                       desc: 'Tech domain contacts codes'
         param :dnskeys_attributes, Array, required: false, desc: 'DNSSEC keys for domain' do
-          param :flags, String, required: true, desc: 'Flag of DNSSEC key'
-          param :protocol, String, required: true, desc: 'Protocol of DNSSEC key'
-          param :alg, String, required: true, desc: 'Algorithm of DNSSEC key'
-          param :public_key, String, required: true, desc: 'Public key of DNSSEC key'
+          param_group :dns_keys_apidoc, Repp::V1::Domains::DnssecController
         end
       end
       returns code: 200, desc: 'Successful domain registration response' do
@@ -61,7 +60,9 @@ module Repp
         @domain = Epp::Domain.new
         action = Actions::DomainCreate.new(@domain, domain_create_params)
 
+        # rubocop:disable Style/AndOr
         handle_errors(@domain) and return unless action.call
+        # rubocop:enable Style/AndOr
 
         render_success(data: { domain: { name: @domain.name } })
       end
@@ -72,7 +73,8 @@ module Repp
       param :domain, Hash, required: true, desc: 'Changes of domain object' do
         param :registrant, Hash, required: false, desc: 'New registrant object' do
           param :code, String, required: true, desc: 'New registrant contact code'
-          param :verified, [true, false], required: false, desc: 'Registrant change is already verified'
+          param :verified, [true, false], required: false,
+                                          desc: 'Registrant change is already verified'
         end
         param :auth_info, String, required: false, desc: 'New authorization code'
       end
@@ -119,13 +121,17 @@ module Repp
       api :DELETE, '/repp/v1/domains/:domain_name'
       desc 'Delete specific domain'
       param :delete, Hash, required: true, desc: 'Object holding verified key' do
-        param :verified, [true, false], required: true, desc: 'Whether to ask registrant verification or not'
+        param :verified, [true, false], required: true,
+                                        desc: 'Whether to ask registrant verification or not'
       end
       def destroy
         action = Actions::DomainDelete.new(@domain, params, current_user.registrar)
-        handle_errors(@domain) and return unless action.call
 
-        render_success(data: { domain: { name: @domain.name }})
+        # rubocop:disable Style/AndOr
+        handle_errors(@domain) and return unless action.call
+        # rubocop:enable Style/AndOr
+
+        render_success(data: { domain: { name: @domain.name } })
       end
 
       private
@@ -202,8 +208,8 @@ module Repp
       end
 
       def domain_create_params
-        params.require(:domain).require([:name, :registrant_id, :period, :period_unit])
-        params.require(:domain).permit(:name, :registrant_id, :period, :period_unit, :registrar_id)
+        params.require(:domain).require(%i[name registrant_id period period_unit])
+        params.require(:domain).permit(%i[name registrant_id period period_unit registrar_id])
       end
     end
   end
diff --git a/app/controllers/repp/v1/registrar/notifications_controller.rb b/app/controllers/repp/v1/registrar/notifications_controller.rb
index 0f6808710..2c5ced56b 100644
--- a/app/controllers/repp/v1/registrar/notifications_controller.rb
+++ b/app/controllers/repp/v1/registrar/notifications_controller.rb
@@ -8,10 +8,12 @@ module Repp
         desc 'Get the latest unread poll message'
         def index
           @notification = current_user.unread_notifications.order('created_at DESC').take
-          render_success(data: nil) and return unless @notification
 
-          data = @notification.as_json(only: [:id, :text, :attached_obj_id,
-                                              :attached_obj_type])
+          # rubocop:disable Style/AndOr
+          render_success(data: nil) and return unless @notification
+          # rubocop:enable Style/AndOr
+
+          data = @notification.as_json(only: %i[id text attached_obj_id attached_obj_type])
 
           render_success(data: data)
         end
@@ -20,8 +22,7 @@ module Repp
         desc 'Get a specific poll message'
         def show
           @notification = current_user.registrar.notifications.find(params[:id])
-          data = @notification.as_json(only: [:id, :text, :attached_obj_id,
-                                              :attached_obj_type])
+          data = @notification.as_json(only: %i[id text attached_obj_id attached_obj_type])
 
           render_success(data: data)
         end
@@ -29,10 +30,12 @@ module Repp
         api :PUT, '/repp/v1/registrar/notifications'
         desc 'Mark poll message as read'
         param :notification, Hash, required: true do
-          param :read, [true], required: true, desc: "Set as true to mark as read"
+          param :read, [true], required: true, desc: 'Set as true to mark as read'
         end
         def update
+          # rubocop:disable Style/AndOr
           handle_errors(@notification) and return unless @notification.mark_as_read
+          # rubocop:enable Style/AndOr
 
           render_success(data: { notification_id: @notification.id, read: true })
         end
diff --git a/app/interactions/domains/check_balance/single_domain.rb b/app/interactions/domains/check_balance/single_domain.rb
index de8f24d18..607913e92 100644
--- a/app/interactions/domains/check_balance/single_domain.rb
+++ b/app/interactions/domains/check_balance/single_domain.rb
@@ -13,7 +13,7 @@ module Domains
 
         domain.add_epp_error(2104, nil, nil, I18n.t(:active_price_missing_for_this_operation))
         errors.add(:domain, I18n.t(:active_price_missing_for_operation_with_domain,
-          domain: domain.name))
+                                   domain: domain.name))
         false
       end
 
diff --git a/app/models/actions/domain_create.rb b/app/models/actions/domain_create.rb
index f028ec4ef..274a070fb 100644
--- a/app/models/actions/domain_create.rb
+++ b/app/models/actions/domain_create.rb
@@ -82,7 +82,9 @@ module Actions
     end
 
     def assign_nameservers
-      domain.nameservers_attributes = params[:nameservers_attributes] if params[:nameservers_attributes]
+      return unless params[:nameservers_attributes]
+
+      domain.nameservers_attributes = params[:nameservers_attributes]
     end
 
     def assign_contact(contact_code, admin: true)
diff --git a/app/models/actions/domain_renew.rb b/app/models/actions/domain_renew.rb
index 1069e4a66..ba1ac8fb3 100644
--- a/app/models/actions/domain_renew.rb
+++ b/app/models/actions/domain_renew.rb
@@ -21,9 +21,9 @@ module Actions
       end
 
       task = Domains::BulkRenew::SingleDomainRenew.run(domain: domain,
-        period: params[:period],
-        unit: params[:period_unit],
-        registrar: user)
+                                                       period: params[:period],
+                                                       unit: params[:period_unit],
+                                                       registrar: user)
 
       task.valid?
     end
diff --git a/lib/serializers/repp/domain.rb b/lib/serializers/repp/domain.rb
index b8afa6693..5821e1568 100644
--- a/lib/serializers/repp/domain.rb
+++ b/lib/serializers/repp/domain.rb
@@ -13,7 +13,7 @@ module Serializers
           updated_at: obj.updated_at, expire_time: obj.expire_time, outzone_at: obj.outzone_at,
           delete_date: obj.delete_date, force_delete_date: obj.force_delete_date,
           authorization_code: obj.auth_info, contacts: contacts, nameservers: nameservers,
-          dnssec_keys: dnssec_keys, statuses: obj.statuses,
+          dnssec_keys: dnssec_keys, statuses: obj.statuses
         }
 
         json