diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 00000000..56bb8d1d
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,142 @@
+import csrf from 'csrf';
+
+declare class AuthResponse {
+    constructor(params: AuthResponse.AuthResponseParams);
+    processResponse(response: Object): void;
+    getToken(): Token;
+    text(): string;
+    status(): number;
+    headers(): Object;
+    valid(): boolean;
+    getJson(): Object;
+    get_intuit_tid(): string;
+    isContentType(): boolean;
+    getContentType(): string;
+    isJson(): boolean;
+
+}
+
+declare namespace AuthResponse {
+    export interface AuthResponseParams {
+        token?: Token;
+        response?: Response;
+        body?: string;
+        json?: Object;
+        intuit_tid?: string;
+    }
+}
+
+declare class Token implements Token.TokenData {
+    latency: number;
+    realmId: string;
+    token_type: string;
+    access_token: string;
+    refresh_token: string;
+    expires_in: number;
+    x_refresh_token_expires_in: number;
+    id_token: string;
+    createdAt: string;
+    accessToken(): string;
+    refreshToken(): string;
+    tokenType(): string;
+    getToken(): Token.TokenData;
+    setToken(tokenData: Token.TokenData): Token;
+    clearToken(): Token;
+    isAccessTokenValid(): boolean;
+    isRefreshTokenValid(): boolean;
+}
+
+declare namespace Token {
+    export interface TokenData {
+        realmId?: string;
+        token_type?: string;
+        access_token?: string;
+        refresh_token?: string;
+        expires_in: number;
+        x_refresh_token_expires_in: number;
+        id_token?: string;
+        latency: number;
+        createdAt: string;
+    }
+}
+
+declare class OAuthClient {
+    constructor(config: OAuthClient.OAuthClientConfig);
+    authHeader(): string;
+    authorizeUri(params: OAuthClient.AuthorizeParams): string;
+    createError(e: Error, authResponse?: AuthResponse): OAuthClient.OAuthClientError;
+    createToken(uri: string): Promise<AuthResponse>;
+    getKeyFromJWKsURI(id_token: string, kid: string, request: Request): Promise<object | string>;
+    getTokenRequest(request: Request): Promise<AuthResponse>;
+    getUserInfo(params?: OAuthClient.GetUserInfoParams): Promise<AuthResponse>;
+    isAccessTokenValid(): boolean;
+    loadResponse(request: Request): Promise<Response>;
+    loadResponseFromJWKsURI(request: Request): Promise<Response>;
+    log(level: string, message: string, messageData: any): void;
+    makeApiCall(params?: OAuthClient.MakeApiCallParams): Promise<AuthResponse>;
+    refresh(): Promise<AuthResponse>;
+    refreshUsingToken(refresh_token: string): Promise<AuthResponse>;
+    revoke(params?: OAuthClient.RevokeParams): Promise<AuthResponse>;
+    setToken(params: Token.TokenData): Token;
+    validateIdToken(params?: OAuthClient.ValidateIdTokenParams): Promise<Response>;
+    validateToken(): void;
+}
+
+declare namespace OAuthClient {
+    export interface OAuthClientConfig {
+        clientId: string;
+        clientSecret: string;
+        redirectUri?: string;
+        environment?: string;
+        token: Token;
+        logging: boolean;
+    }
+
+    export enum environment {
+        sandbox = 'https://sandbox-quickbooks.api.intuit.com/',
+        production = 'https://quickbooks.api.intuit.com/'
+    }
+
+    export enum scopes {
+        Accounting = 'com.intuit.quickbooks.accounting',
+        Payment = 'com.intuit.quickbooks.payment',
+        Payroll = 'com.intuit.quickbooks.payroll',
+        TimeTracking = 'com.intuit.quickbooks.payroll.timetracking',
+        Benefits = 'com.intuit.quickbooks.payroll.benefits',
+        Profile = 'profile',
+        Email = 'email',
+        Phone = 'phone',
+        Address = 'address',
+        OpenId = 'openid',
+        Intuit_name = 'intuit_name'
+    }
+
+    export interface AuthorizeParams {
+        scope: scopes | scopes[] | string;
+        state?: csrf | string;
+    }
+
+    export interface RevokeParams {
+        access_token?: string;
+        refresh_token?: string;
+    }
+
+    export interface GetUserInfoParams { }
+
+    export interface MakeApiCallParams {
+        url: string;
+    }
+
+    export interface ValidateIdTokenParams {
+        id_token?: string;
+    }
+
+    export interface OAuthClientError extends Error {
+        intuit_tid: string;
+        authResponse: AuthResponse;
+        originalMessage: string;
+        error_description: string;
+    }
+}
+
+export = OAuthClient;
diff --git a/package.json b/package.json
index 239c74a4..b2c46172 100644
--- a/package.json
+++ b/package.json
@@ -3,10 +3,11 @@
   "version": "3.0.2",
   "description": "Intuit Node.js client for OAuth2.0 and OpenIDConnect",
   "main": "./src/OAuthClient.js",
+  "types": "./index.d.ts",
   "scripts": {
     "start": "node index.js",
     "karma": "karma start karma.conf.js",
-    "test": "nyc mocha",
+    "test": "nyc mocha && npm run test-ts",
     "snyk": "snyk test",
     "lint": "eslint .",
     "fix": "eslint . --fix",
@@ -15,8 +16,9 @@
     "test-debug": "mocha --inspect-brk --watch test",
     "show-coverage": "npm test; open -a 'Google Chrome' coverage/index.html",
     "clean-install": "rm -rf node_modules && npm install",
-    "snyk-protect": "snyk protect",
-    "prepublish": "npm run snyk-protect"
+    "snyk-protect": "snyk-protect",
+    "prepublish": "npm run snyk-protect",
+    "test-ts": "mocha -r ts-node/register test/**/*.test.ts"
   },
   "keywords": [
     "intuit-oauth",
@@ -69,13 +71,19 @@
   "dependencies": {
     "atob": "2.1.2",
     "csrf": "^3.0.4",
-    "jsonwebtoken": "^8.3.0",
-    "popsicle": "10.0.1",
+    "express": "^4.17.1",
+    "jsonwebtoken": "^9.0.2",
+    "n": "^10.1.0",
+    "popsicle": "^12.1.2",
     "query-string": "^6.12.1",
     "rsa-pem-from-mod-exp": "^0.8.4",
     "winston": "^3.1.0"
   },
   "devDependencies": {
+    "@snyk/protect": "^1.657.0",
+    "@types/chai": "^4.2.14",
+    "@types/express": "^4.17.1",
+    "@types/mocha": "^8.0.3",
     "btoa": "^1.2.1",
     "chai": "^4.1.2",
     "chai-as-promised": "^7.1.1",
@@ -83,12 +91,13 @@
     "eslint-config-airbnb-base": "^14.1.0",
     "eslint-config-prettier": "^6.11.0",
     "eslint-plugin-import": "^2.20.2",
-    "mocha": "^7.1.2",
+    "mocha": "^11.1.0",
     "nock": "^9.2.3",
     "nyc": "^15.0.1",
     "prettier": "^2.0.5",
     "sinon": "^9.0.2",
-    "snyk": "^1.316.1"
+    "ts-node": "^9.0.0",
+    "typescript": "^4.9.5"
   },
   "snyk": true
 }
diff --git a/sample/.env.example b/sample/javascript/.env.example
similarity index 100%
rename from sample/.env.example
rename to sample/javascript/.env.example
diff --git a/sample/README.md b/sample/javascript/README.md
similarity index 100%
rename from sample/README.md
rename to sample/javascript/README.md
diff --git a/sample/app.js b/sample/javascript/app.js
similarity index 100%
rename from sample/app.js
rename to sample/javascript/app.js
diff --git a/sample/package.json b/sample/javascript/package.json
similarity index 100%
rename from sample/package.json
rename to sample/javascript/package.json
diff --git a/sample/typescript/.env.example b/sample/typescript/.env.example
new file mode 100644
index 00000000..10396306
--- /dev/null
+++ b/sample/typescript/.env.example
@@ -0,0 +1,5 @@
+# Environment Variables.
+
+
+PORT=
+NGROK_ENABLED= true
diff --git a/sample/typescript/README.md b/sample/typescript/README.md
new file mode 100644
index 00000000..c88c602b
--- /dev/null
+++ b/sample/typescript/README.md
@@ -0,0 +1,96 @@
+
+[![Sample Banner](./public/images/Sample.png)][ss1]
+
+Intuit OAuth2.0 Sample - NodeJS
+==========================================================
+
+## Overview
+
+This is a `sample` app built using Node.js and Express Framework to showcase how to Authorize and Authenticate using Intuit's OAuth2.0 Client library.
+
+## Installation
+
+### Requirements
+
+* [Node.js](http://nodejs.org) >= 6.0.0
+* [Intuit Developer](https://developer.intuit.com) Account
+
+### Via Github Repo (Recommended)
+
+```bash
+$ cd sample
+$ npm install
+```
+
+## Configuration
+
+Copy the contents from `.env.example` to `.env` within the sample directory:
+```bash
+$ cp .env.example .env
+```
+Edit the `.env` file to add your:  
+
+
+* **PORT:(optional)** Optional port number for the app to be served
+* **NGROK_ENABLED:(optional)** By default it is set to `false`. If you want to serve the Sample App over HTTPS ( which is mandatory if you want to test this app using Production Credentials), set the variable to `true`
+
+
+
+### TLS / SSL (**optional**)
+
+If you want your enpoint to be exposed over the internet. The easiest way to do that while you are still developing your code locally is to use [ngrok](https://ngrok.com/).  
+
+You dont have to worry about installing ngrok. The sample application does that for you.   
+1. Just set `NGROK_ENABLED` = `true` in `.env` 
+
+
+## Usage
+
+```bash
+$ npm start
+```
+
+### Without ngrok (if you are using localhost i.e `NGROK_ENABLED`=`false` in `.env`)
+You will see an URL as below:
+```bash
+💳 Step 1 : Paste this URL in your browser : http://localhost:8000
+💳 Step 2 : Copy and Paste the clientId and clientSecret from : https://developer.intuit.com
+💳 Step 3 : Copy Paste this callback URL into `redirectURI` : http://localhost:8000/callback
+💻 Step 4 : Make Sure this redirect URI is also listed under the Redirect URIs on your app in : https://developer.intuit.com
+```
+
+### With ngrok (if you are using ngrok i.e `NGROK_ENABLED`=`true` in `.env`)
+
+Your will see an URL as below : 
+```bash
+💳 Step 1 : Paste this URL in your browser :  https://9b4ee833.ngrok.io 
+💳 Step 2 : Copy and Paste the clientId and clientSecret from : https://developer.intuit.com
+💳 Step 3 : Copy Paste this callback URL into `redirectURI` : https://9b4ee833.ngrok.io/callback
+💻 Step 4 : Make Sure this redirect URI is also listed under the Redirect URIs on your app in : https://developer.intuit.com
+```
+
+Click on the URL and follow through the instructions given in the sample app.
+
+
+## Links
+
+Project Repo
+
+* https://github.com/intuit/oauth-jsclient
+
+Intuit OAuth2.0 API Reference
+
+* https://developer.intuit.com/app/developer/qbo/docs/develop/authentication-and-authorization/oauth-2.0
+
+Intuit OAuth2.0 Playground
+
+* https://developer.intuit.com/app/developer/playground
+
+## Contributions
+
+Any reports of problems, comments or suggestions are most welcome.
+
+Please report these on [Issue Tracker in Github](https://github.com/intuit/oauth-jsclient/issues).
+
+
+[ss1]: https://help.developer.intuit.com/s/samplefeedback?cid=9010&repoName=Intuit-OAuth2.0-Sample-NodeJS
diff --git a/sample/typescript/dist/app.js b/sample/typescript/dist/app.js
new file mode 100644
index 00000000..8c8f765d
--- /dev/null
+++ b/sample/typescript/dist/app.js
@@ -0,0 +1,140 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+var dotenv_1 = __importDefault(require("dotenv"));
+var express_1 = __importDefault(require("express"));
+var path_1 = __importDefault(require("path"));
+var intuit_oauth_1 = __importDefault(require("intuit-oauth"));
+var body_parser_1 = __importDefault(require("body-parser"));
+dotenv_1.default.config();
+var app = express_1.default();
+var ngrok = (process.env.NGROK_ENABLED === "true") ? require('ngrok') : null;
+/**
+ * Configure View and Handlebars
+ */
+app.use(body_parser_1.default.urlencoded({ extended: true }));
+app.use(express_1.default.static(path_1.default.join(__dirname, '../../public')));
+app.engine('html', require('ejs').renderFile);
+app.set('view engine', 'html');
+app.use(body_parser_1.default.json());
+var urlencodedParser = body_parser_1.default.urlencoded({ extended: false });
+/**
+ * App Variables
+ * @type {null}
+ */
+var oauth2_token_json = null, redirectUri = '';
+/**
+ * Instantiate new Client
+ * @type {OAuthClient}
+ */
+var oauthClient = null;
+/**
+ * Home Route
+ */
+app.get('/', function (req, res) {
+    res.render('index');
+});
+/**
+ * Get the AuthorizeUri
+ */
+app.get('/authUri', urlencodedParser, function (req, res) {
+    oauthClient = new intuit_oauth_1.default({
+        clientId: req.query.json.clientId,
+        clientSecret: req.query.json.clientSecret,
+        environment: req.query.json.environment,
+        redirectUri: req.query.json.redirectUri
+    });
+    var authUri = oauthClient.authorizeUri({ scope: [intuit_oauth_1.default.scopes.Accounting], state: 'intuit-test' });
+    res.send(authUri);
+});
+/**
+ * Handle the callback to extract the `Auth Code` and exchange them for `Bearer-Tokens`
+ */
+app.get('/callback', function (req, res) {
+    oauthClient.createToken(req.url)
+        .then(function (authResponse) {
+        oauth2_token_json = JSON.stringify(authResponse.getJson(), null, 2);
+    })
+        .catch(function (e) {
+        console.error(e);
+    });
+    res.send('');
+});
+/**
+ * Display the token : CAUTION : JUST for sample purposes
+ */
+app.get('/retrieveToken', function (req, res) {
+    res.send(oauth2_token_json);
+});
+/**
+ * Refresh the access-token
+ */
+app.get('/refreshAccessToken', function (req, res) {
+    oauthClient.refresh()
+        .then(function (authResponse) {
+        console.log('The Refresh Token is  ' + JSON.stringify(authResponse.getJson()));
+        oauth2_token_json = JSON.stringify(authResponse.getJson(), null, 2);
+        res.send(oauth2_token_json);
+    })
+        .catch(function (e) {
+        console.error(e);
+    });
+});
+/**
+ * getCompanyInfo ()
+ */
+app.get('/getCompanyInfo', function (req, res) {
+    var companyID = oauthClient.getToken().realmId;
+    var url = oauthClient.environment == 'sandbox' ? intuit_oauth_1.default.environment.sandbox : intuit_oauth_1.default.environment.production;
+    oauthClient.makeApiCall({ url: url + 'v3/company/' + companyID + '/companyinfo/' + companyID })
+        .then(function (authResponse) {
+        console.log("authResponse: ", authResponse);
+        console.log("The response for API call is :" + JSON.stringify(authResponse.json));
+        res.send(authResponse.json);
+    })
+        .catch(function (e) {
+        console.error(e);
+    });
+});
+/**
+ * disconnect ()
+ */
+app.get('/disconnect', function (req, res) {
+    console.log('The disconnect called ');
+    var authUri = oauthClient.authorizeUri({ scope: [intuit_oauth_1.default.scopes.OpenId, intuit_oauth_1.default.scopes.Email], state: 'intuit-test' });
+    res.redirect(authUri);
+});
+/**
+ * Start server on HTTP (will use ngrok for HTTPS forwarding)
+ */
+var server = app.listen(process.env.PORT || 8000, function () {
+    var address = server.address();
+    console.log("\uD83D\uDCBB Server listening on port " + address.port);
+    if (!ngrok) {
+        redirectUri = "" + address.port + '/callback';
+        console.log("\uD83D\uDCB3  Step 1 : Paste this URL in your browser : " + 'http://localhost:' + ("" + address.port));
+        console.log('💳  Step 2 : Copy and Paste the clientId and clientSecret from : https://developer.intuit.com');
+        console.log("\uD83D\uDCB3  Step 3 : Copy Paste this callback URL into redirectURI :" + 'http://localhost:' + ("" + address.port) + '/callback');
+        console.log("\uD83D\uDCBB  Step 4 : Make Sure this redirect URI is also listed under the Redirect URIs on your app in : https://developer.intuit.com");
+    }
+});
+/**
+ * Optional : If NGROK is enabled
+ */
+if (ngrok) {
+    console.log("NGROK Enabled");
+    ngrok.connect({ addr: process.env.PORT || 8000 }, function (err, url) {
+        if (err) {
+            process.exit(1);
+        }
+        else {
+            redirectUri = url + '/callback';
+            console.log("\uD83D\uDCB3 Step 1 : Paste this URL in your browser :  " + url);
+            console.log('💳 Step 2 : Copy and Paste the clientId and clientSecret from : https://developer.intuit.com');
+            console.log("\uD83D\uDCB3 Step 3 : Copy Paste this callback URL into redirectURI :  " + redirectUri);
+            console.log("\uD83D\uDCBB Step 4 : Make Sure this redirect URI is also listed under the Redirect URIs on your app in : https://developer.intuit.com");
+        }
+    });
+}
diff --git a/sample/typescript/package.json b/sample/typescript/package.json
new file mode 100644
index 00000000..c9d74b93
--- /dev/null
+++ b/sample/typescript/package.json
@@ -0,0 +1,27 @@
+{
+  "name": "intuit-nodejsclient",
+  "version": "1.0.0",
+  "description": "A sample NodeJs typescript application to demonstrate the use of the client OAuth library",
+  "scripts": {
+    "start": "tsc && node dist/app",
+    "test": "./node_modules/mocha/bin/mocha test/**/*-test.js --reporter spec"
+  },
+  "author": "anil_kumar3@intuit.com",
+  "license": "APACHE",
+  "homepage": "https://github.intuit.com/abisalehalliprasan/oauth-jsclient",
+  "dependencies": {
+    "body-parser": "latest",
+    "dotenv": "^8.2.0",
+    "ejs": "^3.1.10",
+    "express": "^4.14.0",
+    "express-session": "^1.14.2",
+    "intuit-oauth": "^4.2.0",
+    "ngrok": "^5.0.0-beta.2",
+    "path": "^0.12.7"
+  },
+  "devDependencies": {
+    "@types/body-parser": "^1.17.1",
+    "@types/express": "^4.17.1",
+    "typescript": "^3.6.4"
+  }
+}
diff --git a/sample/typescript/src/app.ts b/sample/typescript/src/app.ts
new file mode 100644
index 00000000..acdff3b5
--- /dev/null
+++ b/sample/typescript/src/app.ts
@@ -0,0 +1,178 @@
+import dotenv from 'dotenv';
+import express from 'express';
+import path from 'path';
+import OAuthClient from 'intuit-oauth';
+import bodyParser from 'body-parser';
+import { AddressInfo } from 'net';
+
+dotenv.config();
+const app = express();
+const ngrok = (process.env.NGROK_ENABLED==="true") ? require('ngrok'):null;
+
+
+/**
+ * Configure View and Handlebars
+ */
+app.use(bodyParser.urlencoded({extended: true}));
+app.use(express.static(path.join(__dirname, '../../public')));
+app.engine('html', require('ejs').renderFile);
+app.set('view engine', 'html');
+app.use(bodyParser.json())
+
+const urlencodedParser = bodyParser.urlencoded({ extended: false });
+
+/**
+ * App Variables
+ * @type {null}
+ */
+let oauth2_token_json = null,
+    redirectUri = '';
+
+
+/**
+ * Instantiate new Client
+ * @type {OAuthClient}
+ */
+
+let oauthClient = null;
+
+
+/**
+ * Home Route
+ */
+app.get('/', function(req, res) {
+
+    res.render('index');
+});
+
+/**
+ * Get the AuthorizeUri
+ */
+app.get('/authUri', urlencodedParser, function(req,res) {
+
+    oauthClient = new OAuthClient({
+        clientId: req.query.json.clientId,
+        clientSecret: req.query.json.clientSecret,
+        environment: req.query.json.environment,
+        redirectUri: req.query.json.redirectUri
+    });
+
+    const authUri = oauthClient.authorizeUri({scope:[OAuthClient.scopes.Accounting],state:'intuit-test'});
+    res.send(authUri);
+});
+
+
+/**
+ * Handle the callback to extract the `Auth Code` and exchange them for `Bearer-Tokens`
+ */
+app.get('/callback', function(req, res) {
+
+    oauthClient.createToken(req.url)
+       .then(function(authResponse) {
+             oauth2_token_json = JSON.stringify(authResponse.getJson(), null,2);
+         })
+        .catch(function(e) {
+             console.error(e);
+         });
+
+    res.send('');
+
+});
+
+/**
+ * Display the token : CAUTION : JUST for sample purposes
+ */
+app.get('/retrieveToken', function(req, res) {
+    res.send(oauth2_token_json);
+});
+
+
+/**
+ * Refresh the access-token
+ */
+app.get('/refreshAccessToken', function(req,res){
+
+    oauthClient.refresh()
+        .then(function(authResponse){
+            console.log('The Refresh Token is  '+ JSON.stringify(authResponse.getJson()));
+            oauth2_token_json = JSON.stringify(authResponse.getJson(), null,2);
+            res.send(oauth2_token_json);
+        })
+        .catch(function(e) {
+            console.error(e);
+        });
+
+
+});
+
+/**
+ * getCompanyInfo ()
+ */
+app.get('/getCompanyInfo', function(req,res){
+
+
+    const companyID = oauthClient.getToken().realmId;
+
+    const url = oauthClient.environment == 'sandbox' ? OAuthClient.environment.sandbox : OAuthClient.environment.production ;
+
+    oauthClient.makeApiCall({url: url + 'v3/company/' + companyID +'/companyinfo/' + companyID})
+        .then(function(authResponse){
+            console.log("The response for API call is :"+JSON.stringify(authResponse));
+            res.send(JSON.parse(authResponse.text()));
+        })
+        .catch(function(e) {
+            console.error(e);
+        });
+});
+
+/**
+ * disconnect ()
+ */
+app.get('/disconnect', function(req,res){
+
+  console.log('The disconnect called ');
+  const authUri = oauthClient.authorizeUri({scope:[OAuthClient.scopes.OpenId,OAuthClient.scopes.Email],state:'intuit-test'});
+  res.redirect(authUri);
+
+});
+
+
+
+/**
+ * Start server on HTTP (will use ngrok for HTTPS forwarding)
+ */
+const server = app.listen(process.env.PORT || 8000, () => {
+    const address = server.address() as AddressInfo;
+    console.log(`💻 Server listening on port ${address.port}`);
+if(!ngrok){
+    redirectUri = `${address.port}` + '/callback';
+    console.log(`💳  Step 1 : Paste this URL in your browser : ` + 'http://localhost:' + `${address.port}`);
+    console.log('💳  Step 2 : Copy and Paste the clientId and clientSecret from : https://developer.intuit.com')
+    console.log(`💳  Step 3 : Copy Paste this callback URL into redirectURI :` + 'http://localhost:' + `${address.port}` + '/callback');
+    console.log(`💻  Step 4 : Make Sure this redirect URI is also listed under the Redirect URIs on your app in : https://developer.intuit.com`);
+}
+
+});
+
+/**
+ * Optional : If NGROK is enabled
+ */
+if (ngrok) {
+
+    console.log("NGROK Enabled");
+    ngrok.connect({addr: process.env.PORT || 8000}, (err, url) => {
+            if (err) {
+                process.exit(1);
+            }
+            else {
+                redirectUri = url + '/callback';
+                console.log(`💳 Step 1 : Paste this URL in your browser :  ${url}`);
+                console.log('💳 Step 2 : Copy and Paste the clientId and clientSecret from : https://developer.intuit.com')
+                console.log(`💳 Step 3 : Copy Paste this callback URL into redirectURI :  ${redirectUri}`);
+                console.log(`💻 Step 4 : Make Sure this redirect URI is also listed under the Redirect URIs on your app in : https://developer.intuit.com`);
+
+            }
+        }
+    );
+}
+
diff --git a/sample/typescript/tsconfig.json b/sample/typescript/tsconfig.json
new file mode 100644
index 00000000..e77f3714
--- /dev/null
+++ b/sample/typescript/tsconfig.json
@@ -0,0 +1,65 @@
+{
+  "compilerOptions": {
+    /* Basic Options */
+    "target": "es5",                          /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017', 'ES2018', 'ES2019' or 'ESNEXT'. */
+    "module": "commonjs",                     /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
+    // "lib": [],                             /* Specify library files to be included in the compilation. */
+    "allowJs": true,                       /* Allow javascript files to be compiled. */
+    "checkJs": true,                       /* Report errors in .js files. */
+    // "jsx": "preserve",                     /* Specify JSX code generation: 'preserve', 'react-native', or 'react'. */
+    // "declaration": true,                   /* Generates corresponding '.d.ts' file. */
+    // "declarationMap": true,                /* Generates a sourcemap for each corresponding '.d.ts' file. */
+    // "sourceMap": true,                     /* Generates corresponding '.map' file. */
+    // "outFile": "./",                       /* Concatenate and emit output to single file. */
+    "outDir": "dist/",                        /* Redirect output structure to the directory. */
+    // "rootDir": "./",                       /* Specify the root directory of input files. Use to control the output directory structure with --outDir. */
+    // "composite": true,                     /* Enable project compilation */
+    // "incremental": true,                   /* Enable incremental compilation */
+    // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
+    // "removeComments": true,                /* Do not emit comments to output. */
+    // "noEmit": true,                        /* Do not emit outputs. */
+    // "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
+    // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
+    // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */
+
+    /* Strict Type-Checking Options */
+    "strict": true,                           /* Enable all strict type-checking options. */
+    "noImplicitAny": false,                 /* Raise error on expressions and declarations with an implied 'any' type. */
+    "strictNullChecks": false,              /* Enable strict null checks. */
+    // "strictFunctionTypes": true,           /* Enable strict checking of function types. */
+    // "strictBindCallApply": true,           /* Enable strict 'bind', 'call', and 'apply' methods on functions. */
+    // "strictPropertyInitialization": true,  /* Enable strict checking of property initialization in classes. */
+    // "noImplicitThis": true,                /* Raise error on 'this' expressions with an implied 'any' type. */
+    // "alwaysStrict": true,                  /* Parse in strict mode and emit "use strict" for each source file. */
+
+    /* Additional Checks */
+    // "noUnusedLocals": true,                /* Report errors on unused locals. */
+    // "noUnusedParameters": true,            /* Report errors on unused parameters. */
+    // "noImplicitReturns": true,             /* Report error when not all code paths in function return a value. */
+    // "noFallthroughCasesInSwitch": true,    /* Report errors for fallthrough cases in switch statement. */
+
+    /* Module Resolution Options */
+    // "moduleResolution": "node",            /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
+    // "baseUrl": "./",                       /* Base directory to resolve non-absolute module names. */
+    // "paths": {},                           /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+    // "rootDirs": [],                        /* List of root folders whose combined content represents the structure of the project at runtime. */
+    // "typeRoots": [],                       /* List of folders to include type definitions from. */
+    // "types": [],                           /* Type declaration files to be included in compilation. */
+    // "allowSyntheticDefaultImports": true,  /* Allow default imports from modules with no default export. This does not affect code emit, just typechecking. */
+    "esModuleInterop": true                   /* Enables emit interoperability between CommonJS and ES Modules via creation of namespace objects for all imports. Implies 'allowSyntheticDefaultImports'. */
+    // "preserveSymlinks": true,              /* Do not resolve the real path of symlinks. */
+
+    /* Source Map Options */
+    // "sourceRoot": "",                      /* Specify the location where debugger should locate TypeScript files instead of source locations. */
+    // "mapRoot": "",                         /* Specify the location where debugger should locate map files instead of generated locations. */
+    // "inlineSourceMap": true,               /* Emit a single file with source maps instead of having a separate file. */
+    // "inlineSources": true,                 /* Emit the source alongside the sourcemaps within a single file; requires '--inlineSourceMap' or '--sourceMap' to be set. */
+
+    /* Experimental Options */
+    // "experimentalDecorators": true,        /* Enables experimental support for ES7 decorators. */
+    // "emitDecoratorMetadata": true,         /* Enables experimental support for emitting type metadata for decorators. */
+  },
+  "include": [
+    "src/"
+  ]
+}
diff --git a/src/OAuthClient.js b/src/OAuthClient.js
index 011c251b..b7db8823 100644
--- a/src/OAuthClient.js
+++ b/src/OAuthClient.js
@@ -40,9 +40,10 @@ const Token = require('./access-token/Token');
 /**
  * @constructor
  * @param {string} config.environment
- * @param {string} config.appSecret
- * @param {string} config.appKey
- * @param {string} [config.cachePrefix]
+ * @param {string} config.clientId
+ * @param {string} config.clientSecret
+ * @param {string} [config.redirectUri]
+ * @param {bool} [config.logging]
  */
 function OAuthClient(config) {
   this.environment = config.environment;
diff --git a/test/OAuthClientTest.js b/test/OAuthClientTest.js
index fec50f38..0696a8ec 100644
--- a/test/OAuthClientTest.js
+++ b/test/OAuthClientTest.js
@@ -322,6 +322,26 @@ describe('Tests for OAuthClient', () => {
           );
         });
     });
+    it('Make API Call in Sandbox Environment with headers as parameters', () => {
+      oauthClient.getToken().realmId = '12345';
+      // eslint-disable-next-line no-useless-concat
+      return oauthClient
+        .makeApiCall({
+          url:
+            'https://sandbox-quickbooks.api.intuit.com/v3/company/' +
+            '12345' +
+            '/companyinfo/' +
+            '12345',
+          headers: {
+            Accept: 'application/json',
+          },
+        })
+        .then((authResponse) => {
+          expect(JSON.stringify(authResponse.getJson())).to.be.equal(
+            JSON.stringify(expectedMakeAPICall),
+          );
+        });
+    });
     it('loadResponseFromJWKsURI', () => {
       const request = {
         url: 'https://sandbox-quickbooks.api.intuit.com/v3/company/12345/companyinfo/12345',
diff --git a/test/types.test.ts b/test/types.test.ts
new file mode 100644
index 00000000..0710e5d3
--- /dev/null
+++ b/test/types.test.ts
@@ -0,0 +1,92 @@
+'use strict';
+import { expect } from 'chai';
+import * as OAuthClient from '../src/OAuthClient';
+
+const AuthResponse = require('../src/response/AuthResponse');
+
+describe('OAuthClient type validation tests', () => {
+    let oAuthClientConfig;
+
+    beforeEach(() => {
+        oAuthClientConfig = {
+            clientId: 'clientId',
+            clientSecret: 'clientSecret',
+            environment: 'sandbox',
+            redirectUri: 'http://localhost:8000/callback'
+    };
+    });
+
+    it('environment should have appropriate fields and types', () => {
+        const result = OAuthClient.environment;
+        expect(typeof result).to.equal('object');
+        expect(result.sandbox).to.equal('https://sandbox-quickbooks.api.intuit.com/');
+        expect(result.xyz).to.be.undefined;
+    });
+
+    it('scopes should have appropriate fields and types', () => {
+        const result = OAuthClient.scopes;
+        expect(typeof result).to.equal('object');
+        expect(result.Accounting).to.equal('com.intuit.quickbooks.accounting');
+        expect(typeof result.Accounting).to.equal('string');
+        expect(result.accounting).to.be.undefined;
+    });
+
+    it('OAuthClientConfig should have appropriate fields and types', () => {
+        expect(typeof oAuthClientConfig.clientId).to.equal('string');
+        expect(typeof oAuthClientConfig.clientSecret).to.equal('string');
+        expect(typeof oAuthClientConfig.environment).to.equal('string');
+        expect(typeof oAuthClientConfig.redirectUri).to.equal('string');
+    });
+
+    it('Should create OAuthClient with appropriate fields and types for valid OAuthClientConfig', () => {
+        const oAuthClient = new OAuthClient({
+            oAuthClientConfig
+        });
+        expect(typeof oAuthClient).to.equal('object');
+        expect(typeof oAuthClient.token).to.equal('object');
+        expect(typeof oAuthClient.logging).to.equal('boolean');
+        expect(typeof oAuthClient.logger).to.equal('object');
+        expect(typeof oAuthClient.state).to.equal('object');
+    });
+
+    it('should create new access token instance with appropriate fields and types for valid OAuthClient', () => {
+        const oAuthClient = new OAuthClient({
+            oAuthClientConfig
+        });
+        const accessToken = oAuthClient.getToken();
+        expect(typeof accessToken).to.equal('object');
+        expect(typeof accessToken.realmId).to.equal('string');
+        expect(typeof accessToken.token_type).to.equal('string');
+        expect(typeof accessToken.refresh_token).to.equal('string');
+        expect(typeof accessToken.expires_in).to.equal('number');
+        expect(typeof accessToken.x_refresh_token_expires_in).to.equal('number');
+        expect(typeof accessToken.id_token).to.equal('string');
+        expect(typeof accessToken.latency).to.equal('number');
+        expect(typeof accessToken.createdAt).to.equal('number');
+    });
+
+    it('should create new auth response instance with appropriate fields and types for valid accessToken', () => {
+        const oAuthClient = new OAuthClient({
+            oAuthClientConfig
+        });
+        const accessToken = oAuthClient.getToken();
+        const authResponse = new AuthResponse({ token: accessToken });
+        expect(typeof authResponse.token).to.equal('object');
+        expect(typeof authResponse.response).to.equal('string');
+        expect(typeof authResponse.body).to.equal('string');
+        expect(typeof authResponse.json).to.equal('object');
+        expect(typeof authResponse.intuit_tid).to.equal('string');
+    });
+
+    it('Should create OAuthClientError with appropriate fields and types for empty authResponse', () => {
+        const oAuthClient = new OAuthClient({
+            oAuthClientConfig
+        });
+        const oAuthClientError = oAuthClient.createError(new Error(), null);
+        expect(typeof oAuthClientError.error).to.equal('string');
+        expect(typeof oAuthClientError.authResponse).to.equal('string');
+        expect(typeof oAuthClientError.intuit_tid).to.equal('string');
+        expect(typeof oAuthClientError.originalMessage).to.equal('string');
+        expect(typeof oAuthClientError.error_description).to.equal('string');
+    });
+});