diff --git a/Gemfile b/Gemfile
index 70d7174b6d..0aed6a5fec 100644
--- a/Gemfile
+++ b/Gemfile
@@ -43,7 +43,6 @@ gem "kaminari"
 gem "lodash-rails"
 gem "lograge"
 gem "ougai"
-gem "oj"
 gem "parallel", require: false
 gem "passenger"
 gem "pg", ">= 0.18", "< 2.0"
diff --git a/Gemfile.lock b/Gemfile.lock
index 17c7a222a5..569073c1bf 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -608,7 +608,6 @@ DEPENDENCIES
   memery
   memory_profiler
   mock_redis
-  oj
   ougai
   parallel
   parallel_tests
diff --git a/app/controllers/api/v3/sync_controller.rb b/app/controllers/api/v3/sync_controller.rb
index a25742f911..039cc2bf41 100644
--- a/app/controllers/api/v3/sync_controller.rb
+++ b/app/controllers/api/v3/sync_controller.rb
@@ -11,14 +11,12 @@ def __sync_from_user__(params)
   end
 
   def __sync_to_user__(response_key)
-    records = records_to_sync
-
-    AuditLog.create_logs_async(current_user, records, "fetch", Time.current) unless disable_audit_logs?
+    AuditLog.create_logs_async(current_user, records_to_sync, "fetch", Time.current) unless disable_audit_logs?
     render(
-      json: Oj.dump({
-        response_key => records.map { |record| transform_to_response(record) },
+      json: {
+        response_key => records_to_sync.map { |record| transform_to_response(record) },
         "process_token" => encode_process_token(response_process_token)
-      }, mode: :compat),
+      },
       status: :ok
     )
   end
diff --git a/app/transformers/api/v3/facility_transformer.rb b/app/transformers/api/v3/facility_transformer.rb
index 860f549785..3bc9f67b74 100644
--- a/app/transformers/api/v3/facility_transformer.rb
+++ b/app/transformers/api/v3/facility_transformer.rb
@@ -7,9 +7,7 @@ def to_response(facility)
           "enable_teleconsultation",
           "teleconsultation_phone_number",
           "teleconsultation_isd_code",
-          "teleconsultation_phone_numbers",
-          "organization_name",
-          "facility_group_name")
+          "teleconsultation_phone_numbers")
         .merge(config: {enable_diabetes_management: facility.enable_diabetes_management,
                         enable_teleconsultation: facility.enable_teleconsultation},
                protocol_id: facility.protocol.try(:id))
diff --git a/app/transformers/api/v3/patient_transformer.rb b/app/transformers/api/v3/patient_transformer.rb
index 07e41b801a..e1a559d0ff 100644
--- a/app/transformers/api/v3/patient_transformer.rb
+++ b/app/transformers/api/v3/patient_transformer.rb
@@ -59,10 +59,10 @@ def from_nested_request(payload_attributes)
 
     def to_nested_response(patient)
       Api::V3::Transformer.to_response(patient)
-        .except("address_id",
-          "registration_user_id",
-          "test_data",
-          "deleted_by_user_id")
+        .except("address_id")
+        .except("registration_user_id")
+        .except("test_data")
+        .except("deleted_by_user_id")
         .merge(
           "address" => Api::V3::Transformer.to_response(patient.address),
           "phone_numbers" => patient.phone_numbers.map do |phone_number|
diff --git a/app/transformers/api/v3/transformer.rb b/app/transformers/api/v3/transformer.rb
index 256816fc80..0e4c1db30c 100644
--- a/app/transformers/api/v3/transformer.rb
+++ b/app/transformers/api/v3/transformer.rb
@@ -1,33 +1,31 @@
 class Api::V3::Transformer
   class << self
-    def from_request(payload_attributes)
-      rename_attributes(payload_attributes, from_request_key_mapping)
+    def from_request(attributes_of_payload)
+      rename_attributes(attributes_of_payload, key_mapping)
     end
 
     def to_response(model)
-      rename_attributes(model.attributes, to_response_key_mapping).as_json
+      rename_attributes(model.attributes, inverted_key_mapping).as_json
     end
 
     def rename_attributes(attributes, mapping)
-      replace_keys(attributes.to_hash, mapping).with_indifferent_access
+      mapping = mapping.with_indifferent_access
+      attributes
+        .to_hash
+        .except(*mapping.values)
+        .transform_keys! { |key| mapping[key] || key }
+        .with_indifferent_access
     end
 
-    def replace_keys(hsh, mapping)
-      mapping.each do |k, v|
-        hsh[v] = hsh.delete(k)
-      end
-      hsh
-    end
-
-    def from_request_key_mapping
+    def key_mapping
       {
         "created_at" => "device_created_at",
         "updated_at" => "device_updated_at"
       }
     end
 
-    def to_response_key_mapping
-      from_request_key_mapping.invert
+    def inverted_key_mapping
+      key_mapping.invert
     end
   end
 end
diff --git a/spec/utils.rb b/spec/utils.rb
index fd9030c540..30d484bf13 100644
--- a/spec/utils.rb
+++ b/spec/utils.rb
@@ -20,7 +20,7 @@ def to_json_and_back
 
   def with_payload_keys
     Api::V3::Transformer.rename_attributes(
-      self, Api::V3::Transformer.to_response_key_mapping
+      self, Api::V3::Transformer.inverted_key_mapping
     )
   end
 end