diff --git a/mqtt-mapping-ui/mqtt-mapping/package.json b/mqtt-mapping-ui/mqtt-mapping/package.json
index a56505e9..223e0fd0 100644
--- a/mqtt-mapping-ui/mqtt-mapping/package.json
+++ b/mqtt-mapping-ui/mqtt-mapping/package.json
@@ -1,7 +1,7 @@
 {
   "name": "mqtt-mapping",
   "version": "3.3.3",
-  "description": "Cumulocity plugin to map custom JSON payloads to C8Y payloads.The lugin support both directions: inbound/outbound.",
+  "description": "Cumulocity plugin to map custom JSON payloads to C8Y payloads.The plugin support both directions: inbound/outbound.",
   "repository": {
     "type": "git",
     "url": "git@github.com:SoftwareAG/cumulocity-dynamic-mqtt-mapper.git"
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/c8y-agent.service.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/c8y-agent.service.ts
index c5183c36..28f5dffa 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/c8y-agent.service.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/c8y-agent.service.ts
@@ -50,6 +50,12 @@ export class C8YAgent {
     private alert: AlertService
   ) {}
 
+
+  public initializeCache(): void {
+    this.inventory.initializeCache();
+    this.identity.initializeCache();
+  }
+
   async createMEAO(context: ProcessingContext) {
     let result: any;
     let error: string = "";
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-identity.service.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-identity.service.ts
index 590d6308..d8f368d4 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-identity.service.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-identity.service.ts
@@ -24,7 +24,6 @@ import {
   IExternalIdentity,
   IIdentified,
   IResult,
-  IResultList,
 } from "@c8y/client";
 import * as _ from "lodash";
 import { ProcessingContext } from "../processor/prosessor.model";
@@ -39,6 +38,10 @@ export class FacadeIdentityService {
     private identity: IdentityService
   ) {}
 
+  public initializeCache(): void {
+    this.mockIdentity.initializeCache();
+  }
+
   public async resolveGlobalId2ExternalId(
     managedObjectId: string,
     externalIdType: string,
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-inventory.service.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-inventory.service.ts
index 9e737654..e9f05447 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-inventory.service.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/facade-inventory.service.ts
@@ -32,6 +32,10 @@ export class FacadeInventoryService {
     private inventory: InventoryService
   ) {}
 
+  public initializeCache(): void {
+    this.mockInventory.initializeCache();
+  }
+
   public update(
     managedObject: Partial<IManagedObject>,
     context: ProcessingContext
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/mapping.service.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/mapping.service.ts
index 5b6a7fc1..bc47351d 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/mapping.service.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/core/mapping.service.ts
@@ -118,6 +118,12 @@ export class MappingService {
     return this.reload$;
   }
 
+  initializeCache(dir: Direction): void{
+    if (dir == Direction.INBOUND) {
+      this.jsonProcessorInbound.initializeCache();
+    }
+  }
+
   async updateSubscriptions(sub: C8YAPISubscription): Promise<any> {
     let response = this.client.fetch(
       `${BASE_URL}/${PATH_SUBSCRIPTION_ENDPOINT}`,
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/processor/payload-processor-inbound.service.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/processor/payload-processor-inbound.service.ts
index f6313dba..1769c0c5 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/processor/payload-processor-inbound.service.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/processor/payload-processor-inbound.service.ts
@@ -47,6 +47,10 @@ export abstract class PayloadProcessorInbound {
 
   public abstract extractFromSource(context: ProcessingContext): void;
 
+  public initializeCache(): void {
+    this.c8yClient.initializeCache();
+  }
+
   protected JSONATA = require("jsonata");
 
   public async substituteInTargetAndSend(context: ProcessingContext) {
@@ -114,7 +118,10 @@ export abstract class PayloadProcessorInbound {
         }
 
         if (mapping.targetAPI != API.INVENTORY.name) {
-          if (pathTarget == findDeviceIdentifier(mapping).pathTarget && mapping.mapDeviceIdentifier) {
+          if (
+            pathTarget == findDeviceIdentifier(mapping).pathTarget &&
+            mapping.mapDeviceIdentifier
+          ) {
             let sourceId: string;
             const identity = {
               externalId: substituteValue.value.toString(),
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.html b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.html
index ba3ebf4f..e816fdad 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.html
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.html
@@ -387,8 +387,8 @@
 
   <cdk-step state="final" stepLabel="step3" label="Test mapping">
     <mapping-testing
-      [editorTestingRequestTemplateEmitter]="
-        editorTestingRequestTemplateEmitter
+      [editorTestingPayloadTemplateEmitter]="
+        editorTestingPayloadTemplateEmitter
       "
       [mapping]="getCurrentMapping(true)"
       (testResult)="updateTestResult($event)"
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.ts
index 066c722b..5eec0be5 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-main/mapping-stepper.component.ts
@@ -93,7 +93,7 @@ export class MappingStepperComponent implements OnInit {
   templateFormly: FormGroup = new FormGroup({});
   templateForm: FormGroup;
   templateFormlyFields: FormlyFieldConfig[];
-  editorTestingRequestTemplateEmitter = new EventEmitter<any>();
+  editorTestingPayloadTemplateEmitter = new EventEmitter<any>();
   schemaUpdateSource: EventEmitter<string> = new EventEmitter<any>();
   schemaUpdateTarget: EventEmitter<string> = new EventEmitter<any>();
 
@@ -705,7 +705,7 @@ export class MappingStepperComponent implements OnInit {
       const testSourceTemplate = this.editorSource
         ? this.editorSource.get()
         : {};
-      this.editorTestingRequestTemplateEmitter.emit(testSourceTemplate);
+      this.editorTestingPayloadTemplateEmitter.emit(testSourceTemplate);
       this.onSelectSubstitution(0);
       event.stepper.next();
     }
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.html b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.html
index 26747537..181d77bd 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.html
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.html
@@ -31,11 +31,32 @@ <h4 class="text-center text-medium">Test mapping</h4>
     <div class="card-block p-b-0">
       <div class="container">
         <div class="row">
-          <div class="col-lg-10 col-lg-offset-1">
+          <div class="col-lg-5 col-lg-offset-1 column-right-border">
             <div class="form-group">
               <div style="display: flex">
                 <label for="testResult" translate
-                  >Testing - {{ targetSystem }} Request&nbsp;</label
+                  >{{ sourceSystem }} Payload&nbsp;</label
+                >
+              </div>
+              <mapping-json-editor2
+                [options]="editorOptionsTesting"
+                [data]="testingModel.payload"
+                #editorTestingPayload
+                id="editorTestingPayload"
+              >
+              </mapping-json-editor2>
+              <c8y-messages>
+                <c8y-message *ngIf="testingModel.errorMsg" translate
+                  ><span class="text-warning">{{ testingModel.errorMsg }}</span>
+                </c8y-message>
+              </c8y-messages>
+            </div>
+          </div>
+          <div class="col-lg-5 column-left-border">
+            <div class="form-group">
+              <div style="display: flex">
+                <label for="testResult" translate
+                  >{{ targetSystem }} Request&nbsp;</label
                 >
                 <h6>
                   <span class="badge badge-success">{{
@@ -59,13 +80,19 @@ <h6>
             </div>
           </div>
         </div>
-        <div class="row" [hidden]="mapping.direction == Direction.OUTBOUND">
-          <div class="col-lg-10 col-lg-offset-1">
+        <div class="legend form-block col-lg-10 col-lg-offset-1"></div>
+        <div
+          class="row"
+          [hidden]="mapping.direction == Direction.OUTBOUND"
+        >
+          <!-- <div class="legend form-block col-lg-10 col-lg-offset-1">
+            Substitutions
+          </div> -->
+          <div class="col-lg-5 col-lg-offset-1 column-right-border"></div>
+          <div class="col-lg-5 column-left-border">
             <div class="form-group">
               <div style="display: flex">
-                <label for="testResult" translate
-                  >Testing - {{ targetSystem }} Response&nbsp;</label
-                >
+                <label>{{ targetSystem }} Response&nbsp;</label>
                 <h6>
                   <span class="badge badge-success">{{
                     selectedResult$ | async
@@ -86,7 +113,7 @@ <h6>
     </div>
   </div>
 </div>
-<div class="col-lg-6 col-lg-offset-3 text-center">
+<div class="col-lg-8 col-lg-offset-2 text-center p-b-24 p-t-24">
   <button
     type="button"
     class="btn btn-default"
@@ -108,6 +135,14 @@ <h6>
       {{ testingModel.results.length }}</span
     >
   </button>
+  <button
+    type="button"
+    class="btn btn-default"
+    (click)="onResetTransformation()"
+    [attr.disabled]="isDisabled(!stepperConfiguration.allowTestTransformation)"
+  >
+    Reset Transform
+  </button>
   <button
     type="button"
     class="btn btn-default"
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.ts b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.ts
index 50afdb5b..deea20e8 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.ts
+++ b/mqtt-mapping-ui/mqtt-mapping/src/mqtt-mapping/step-three/mapping-testing.component.ts
@@ -49,12 +49,13 @@ export class MappingStepTestingComponent implements OnInit {
   @Input() mapping: Mapping;
   @Output() testResult: EventEmitter<boolean> = new EventEmitter<boolean>();
   @Input() stepperConfiguration: StepperConfiguration;
-  @Input() editorTestingRequestTemplateEmitter: EventEmitter<any>;
+  @Input() editorTestingPayloadTemplateEmitter: EventEmitter<any>;
 
   Direction = Direction;
   isDisabled = isDisabled;
 
   testingModel: {
+    payload?: any;
     results: C8YRequest[];
     errorMsg?: string;
     request?: any;
@@ -68,9 +69,11 @@ export class MappingStepTestingComponent implements OnInit {
   selectedResult$: BehaviorSubject<number> = new BehaviorSubject<number>(0);
   sourceSystem: string;
   targetSystem: string;
-
+  currentSourceTemplate: any;
   editorOptionsTesting: any = {};
 
+  @ViewChild("editorTestingPayload", { static: false })
+  editorTestingPayload: JsonEditor2Component;
   @ViewChild("editorTestingRequest", { static: false })
   editorTestingRequest: JsonEditor2Component;
   @ViewChild("editorTestingResponse", { static: false })
@@ -108,15 +111,8 @@ export class MappingStepTestingComponent implements OnInit {
       readOnly: true,
     };
 
-    this.editorTestingRequestTemplateEmitter.subscribe((template) => {
-      const editorTestingResponseRef =
-        this.elementRef.nativeElement.querySelector("#editorTestingResponse");
-      if (editorTestingResponseRef != null) {
-        //set schema for editors
-        this.editorTestingResponse.set({} as JSON);
-        editorTestingResponseRef.setAttribute("initialized", "true");
-      }
-
+    this.editorTestingPayloadTemplateEmitter.subscribe((template) => {
+      this.currentSourceTemplate = template;
       const editorTestingRequestRef =
         this.elementRef.nativeElement.querySelector("#editorTestingRequest");
       if (editorTestingRequestRef != null) {
@@ -124,9 +120,15 @@ export class MappingStepTestingComponent implements OnInit {
         this.editorTestingRequest.setSchema(
           getSchema(this.mapping.targetAPI, this.mapping.direction, true)
         );
-        this.testingModel.request = template;
+        this.testingModel = {
+          payload: this.currentSourceTemplate,
+          results: [],
+          selectedResult: -1,
+          request: {},
+          response: {},
+        };
       }
-      console.log("New test template:", template);
+      console.log("New test template:", this.currentSourceTemplate);
     });
   }
 
@@ -181,6 +183,17 @@ export class MappingStepTestingComponent implements OnInit {
     this.onNextTestResult();
   }
 
+  onResetTransformation() {
+    this.testingModel = {
+      payload: this.currentSourceTemplate,
+      results: [],
+      request: {},
+      response: {},
+      selectedResult: -1,
+    };
+    this.mappingService.initializeCache(this.mapping.direction);
+  }
+
   public onNextTestResult() {
     if (
       this.testingModel.selectedResult >=
@@ -189,7 +202,7 @@ export class MappingStepTestingComponent implements OnInit {
       this.testingModel.selectedResult = -1;
     }
     this.testingModel.selectedResult++;
-    this.selectedResult$.next(this.testingModel.selectedResult);
+    this.selectedResult$.next(this.testingModel.selectedResult + 1);
     if (
       this.testingModel.selectedResult >= 0 &&
       this.testingModel.selectedResult < this.testingModel.results.length
diff --git a/mqtt-mapping-ui/mqtt-mapping/src/shared/editor2/jsoneditor2.style.css b/mqtt-mapping-ui/mqtt-mapping/src/shared/editor2/jsoneditor2.style.css
index 25314939..f28b6432 100644
--- a/mqtt-mapping-ui/mqtt-mapping/src/shared/editor2/jsoneditor2.style.css
+++ b/mqtt-mapping-ui/mqtt-mapping/src/shared/editor2/jsoneditor2.style.css
@@ -34,3 +34,7 @@ svg {
   --jse-font-size:   var(--c8y-font-size-small);
   --jse-font-size-mono: var(--c8y-font-size-small);
 }
+
+.jse-main {
+  max-height: 300px;
+}
diff --git a/resources/image/Generic_MQTT_TestTransformation.png b/resources/image/Generic_MQTT_TestTransformation.png
index 99380b22..5f1f5b9a 100644
Binary files a/resources/image/Generic_MQTT_TestTransformation.png and b/resources/image/Generic_MQTT_TestTransformation.png differ