diff --git a/src/index.ts b/src/index.ts
index 41bd23d7..7983c8be 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,4 +1,4 @@
-import { payPayRestSDK } from "./lib/paypay-rest-sdk";
+import { payPayRestSDK, PayPayRestSDK } from "./lib/paypay-rest-sdk";
 
 export = {
   Configure: payPayRestSDK.configure,
@@ -29,4 +29,5 @@ export = {
   CheckCashBackDetails: payPayRestSDK.getCashBackDetails,
   ReversalCashBack: payPayRestSDK.reverseCashBack,
   CheckCashBackReversalDetails: payPayRestSDK.getReverseCashBackDetails,
+  PayPayRestSDK
 };
\ No newline at end of file
diff --git a/src/lib/auth.ts b/src/lib/auth.ts
index 959c64bb..40fd349f 100644
--- a/src/lib/auth.ts
+++ b/src/lib/auth.ts
@@ -4,7 +4,7 @@
  * Right now, we don't have any such checks, this is a dummy file
  */
 
-class Auth {
+export class Auth {
   clientId: string;
   clientSecret: string;
   merchantId?: string;
@@ -28,5 +28,3 @@ class Auth {
     this.merchantId = merchantId;
   }
 }
-
-export let auth = new Auth();
diff --git a/src/lib/paypay-rest-sdk.ts b/src/lib/paypay-rest-sdk.ts
index 77fc9fd4..3ef89e87 100644
--- a/src/lib/paypay-rest-sdk.ts
+++ b/src/lib/paypay-rest-sdk.ts
@@ -1,7 +1,7 @@
 /*
  * Main file, methods that are exposed to end-user
  */
-import { auth } from "./auth";
+import { Auth } from "./auth";
 import { Conf } from "./conf";
 import { httpsClient } from "./httpsClient";
 import { HmacSHA256, enc, algo } from "crypto-js";
@@ -15,10 +15,12 @@ export interface HttpsClientMessage {
 class PayPayRestSDK {
   private options: any = "";
   private productionMode: boolean = false;
+  private auth: Auth;
   private config: Conf;
 
   constructor() {
     this.config = new Conf(this.productionMode);
+    this.auth = new Auth();
   }
 
   /**
@@ -28,7 +30,7 @@ class PayPayRestSDK {
    * @param {string}  merchantId    MERCHANT_ID provided by end-user
    */
   public configure = (clientConfig: { clientId: string; clientSecret: string; merchantId?: string; productionMode: boolean; }) => {
-    auth.setAuth(clientConfig.clientId, clientConfig.clientSecret, clientConfig.merchantId);
+    this.auth.setAuth(clientConfig.clientId, clientConfig.clientSecret, clientConfig.merchantId);
     if (clientConfig.productionMode) {
       this.productionMode = clientConfig.productionMode
     } else {
@@ -72,9 +74,9 @@ class PayPayRestSDK {
     this.options.port = this.config.getPortNumber();
     this.options.headers = {
       "Authorization": header,
-      "X-ASSUME-MERCHANT": auth.merchantId,
+      "X-ASSUME-MERCHANT": this.auth.merchantId,
     };
-    if (isempty.includes(auth.merchantId)) {
+    if (isempty.includes(this.auth.merchantId)) {
       this.options.headers = {
         "Authorization": header,
       };
@@ -106,7 +108,7 @@ class PayPayRestSDK {
     const authHeader = this.createAuthHeader(this.options.method,
       cleanPath,
       this.options.method === "GET" || this.options.method === "DELETE" ? null : input,
-      auth);
+      this.auth);
     this.setHttpsOptions(authHeader);
 
     if (this.options.method === "POST") {
@@ -464,3 +466,4 @@ class PayPayRestSDK {
  * These are methods and variables that are exposed to end-user
  */
 export let payPayRestSDK = new PayPayRestSDK();
+export { PayPayRestSDK };
diff --git a/test/PayPayRestSDK.test.ts b/test/PayPayRestSDK.test.ts
new file mode 100644
index 00000000..5a6b7566
--- /dev/null
+++ b/test/PayPayRestSDK.test.ts
@@ -0,0 +1,26 @@
+import PayPay from "../src";
+
+
+
+test('Unit Test - Check the different fields between two RestSDK instances', async () => {
+    const conf1 = {
+        clientId: 'clientId1',
+        clientSecret: 'clientSecret1',
+        merchantId: '2473982',
+        productionMode: false
+    };
+    const client1 = new PayPay.PayPayRestSDK();
+    client1.configure(conf1)
+
+    const conf2 = {
+        clientId: 'clientId2',
+        clientSecret: 'clientSecret2',
+        merchantId: '3429854',
+        productionMode: true
+    };
+    const client2 = new PayPay.PayPayRestSDK();
+    client2.configure(conf2)
+
+    expect(client1['auth']).not.toEqual(client2['auth']);
+    expect(client1['config']).not.toEqual(client2['config']);
+});