diff --git a/.gitignore b/.gitignore
index fdeae86..e0dd51f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,7 @@
 /yarn.lock
 /node_modules/
 
-/test/config.json
\ No newline at end of file
+/test/config.json
+
+*.js
+*.d.ts
diff --git a/index.js b/index.js
deleted file mode 100644
index 5b9f09d..0000000
--- a/index.js
+++ /dev/null
@@ -1,42 +0,0 @@
-const RestClient = require('./lib/rest_client').RestClient;
-const user = require('./lib/user');
-const cart = require('./lib/cart');
-const order = require('./lib/order');
-const stock = require('./lib/stock');
-const contact = require('./lib/contact');
-const wishlist = require('./lib/wishlist');
-const stockAlert = require('./lib/stock_alert');
-const newsletter = require('./lib/newsletter');
-const address = require('./lib/address');
-
-const MAGENTO_API_VERSION = 'V1';
-
-module.exports.Magento1Client = function (options) {
-  let instance = {
-    addMethods (key, module) {
-      let client = RestClient(options);
-      if (module) {
-        if (this[key])
-          this[key] = Object.assign(this[key], module(client));
-        else
-          this[key] = module(client);
-      }
-    }
-  };
-
-  options.version = MAGENTO_API_VERSION;
-
-  let client = RestClient(options);
-
-  instance.user = user(client);
-  instance.cart = cart(client);
-  instance.order = order(client);
-  instance.stock = stock(client);
-  instance.contact = contact(client);
-  instance.wishlist = wishlist(client);
-  instance.stockAlert = stockAlert(client);
-  instance.newsletter = newsletter(client);
-  instance.address = address(client);
-
-  return instance;
-};
diff --git a/index.ts b/index.ts
new file mode 100644
index 0000000..753eaae
--- /dev/null
+++ b/index.ts
@@ -0,0 +1,50 @@
+import { RestClient, RestClientInstance, RestClientOptions } from "./lib/rest_client";
+import cart, { CartModule } from "./lib/cart";
+import address, { AddressModule } from "./lib/address";
+import order, { OrderModule } from "./lib/order";
+import newsletter, { NewsletterModule } from "./lib/newsletter";
+import user, { UserModule } from "./lib/user";
+import stock, { StockModule } from "./lib/stock";
+import contact, { ContactModule } from "./lib/contact";
+import wishlist, { WishlistModule } from "./lib/wishlist";
+import stockAlert, { StockAlertModule } from "./lib/stock_alert";
+
+const MAGENTO_API_VERSION = 'V1';
+
+interface Magento1ClientInstance {
+  user: UserModule
+  cart: CartModule
+  order: OrderModule
+  stock: StockModule
+  contact: ContactModule
+  wishlist: WishlistModule
+  stockAlert: StockAlertModule
+  newsletter: NewsletterModule
+  address: AddressModule
+  addMethods: (key: string, module: (restClient: RestClientInstance) => Record<string, (...params: any[]) => any>) => void
+}
+
+export function Magento1Client(options: RestClientOptions): Magento1ClientInstance {
+  options.version = MAGENTO_API_VERSION;
+  let client = RestClient(options);
+
+  return {
+    addMethods (key, module) {
+      if (module) {
+        if (this[key])
+          this[key] = Object.assign(this[key], module(client));
+        else
+          this[key] = module(client);
+      }
+    },
+    user: user(client),
+    cart: cart(client),
+    order: order(client),
+    stock: stock(client),
+    contact: contact(client),
+    wishlist: wishlist(client),
+    stockAlert: stockAlert(client),
+    newsletter: newsletter(client),
+    address: address(client)
+  };
+};
diff --git a/lib/address.js b/lib/address.js
deleted file mode 100644
index ef22d35..0000000
--- a/lib/address.js
+++ /dev/null
@@ -1,36 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  let url = 'address/';
-  function getResponse(data){
-    if (data.code === 200){
-      return data.result;
-    }
-
-    return false;
-  }
-  module.list = function (customerToken) {
-    url += `list?token=${customerToken}`
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  },
-  module.update = function (customerToken, addressData) {
-    url += `update?token=${customerToken}`
-    return restClient.post(url, {address: addressData}).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.get = function (customerToken, addressId) {
-    url += `get?token=${customerToken}&addressId=${addressId}`
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.delete = function (customerToken, addressData) {
-    url += `delete?token=${customerToken}`
-    return restClient.post(url, {address: addressData}).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  return module;
-}
diff --git a/lib/address.ts b/lib/address.ts
new file mode 100644
index 0000000..9943aed
--- /dev/null
+++ b/lib/address.ts
@@ -0,0 +1,57 @@
+import { getResponse, RequestResponse, CustomerToken } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface ListCall {
+  (customerToken: CustomerToken): Promise<RequestResponse>
+}
+interface UpdateCall {
+  (customerToken: CustomerToken, addressData: any): Promise<RequestResponse>
+}
+interface GetCall {
+  (customerToken: CustomerToken, addressId: string|number): Promise<RequestResponse>
+}
+interface DeleteCall {
+  (customerToken: CustomerToken, addressData: any): Promise<RequestResponse>
+}
+
+export interface AddressModule {
+  list: ListCall
+  update: UpdateCall
+  get: GetCall
+  delete: DeleteCall
+}
+
+export default function (restClient: RestClientInstance): AddressModule {
+  let url = 'address/';
+
+  const listCall: ListCall = function (customerToken) {
+    url += `list?token=${customerToken}`
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const  updateCall: UpdateCall = function (customerToken, addressData) {
+    url += `update?token=${customerToken}`
+    return restClient.post(url, {address: addressData}).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const getCall: GetCall = function (customerToken, addressId) {
+    url += `get?token=${customerToken}&addressId=${addressId}`
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const deleteCall: DeleteCall = function (customerToken, addressData) {
+    url += `delete?token=${customerToken}`
+    return restClient.post(url, {address: addressData}).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  return {
+    list: listCall,
+    update: updateCall,
+    get: getCall,
+    delete: deleteCall
+  };
+}
diff --git a/lib/cart.js b/lib/cart.js
deleted file mode 100644
index 69d80bd..0000000
--- a/lib/cart.js
+++ /dev/null
@@ -1,82 +0,0 @@
-function isNumeric(val) {
-  return Number(parseFloat(val)).toString() === val;
-}
-
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'cart/';
-  let url = urlPrefix;
-  function getResponse(data){
-    if(data.code === 200){
-      return data.result;
-    }
-    return false;
-  }
-  module.create = (customerToken) => {
-    url += `create?token=${customerToken}`;
-    return restClient.post(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.update = (customerToken, cartId, cartItem) => {
-    url += `update?token=${customerToken}&cartId=${cartId}`;
-    return restClient.post(url, { cartItem: cartItem }).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.applyCoupon = (customerToken, cartId, coupon) => {
-    url += `applyCoupon?token=${customerToken}&cartId=${cartId}&coupon=${coupon}`;
-    return restClient.post(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.deleteCoupon = (customerToken, cartId) => {
-    url += `deleteCoupon?token=${customerToken}&cartId=${cartId}`;
-    return restClient.post(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.delete = (customerToken, cartId, cartItem) => {
-    url += `delete?token=${customerToken}&cartId=${cartId}`;
-    return restClient.post(url, { cartItem: cartItem }).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.pull = (customerToken, cartId) => {
-    url += `pull?token=${customerToken}&cartId=${cartId}`;
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.totals = (customerToken, cartId) => {
-    url += `totals?token=${customerToken}&cartId=${cartId}`;
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.shippingInformation = (customerToken, cartId, body) => {
-    url += `totals?token=${customerToken}&cartId=${cartId}`;
-    return restClient.post(url, body).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.shippingMethods = (customerToken, cartId, address) => {
-    url += `shippingMethods?token=${customerToken}&cartId=${cartId}`;
-    return restClient.post(url, { address: address }).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.paymentMethods = (customerToken, cartId) => {
-    url += `paymentMethods?token=${customerToken}&cartId=${cartId}`;
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.getCoupon = (customerToken, cartId) => {
-    url += `coupon?token=${customerToken}&cartId=${cartId}`;
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  return module;
-}
diff --git a/lib/cart.ts b/lib/cart.ts
new file mode 100644
index 0000000..d3f5238
--- /dev/null
+++ b/lib/cart.ts
@@ -0,0 +1,135 @@
+import { RestClientInstance } from "./rest_client";
+import { getResponse, RequestResponse, CustomerToken } from "./helper";
+
+interface CreateCall {
+  (customerToken: CustomerToken): Promise<RequestResponse>
+}
+interface UpdateCall {
+  (customerToken: CustomerToken, cartId: string|number, cartItem: any): Promise<RequestResponse>
+}
+interface ApplyCouponCall {
+  (customerToken: CustomerToken, cartId: string|number, coupon: string): Promise<RequestResponse>
+}
+interface DeleteCouponCall {
+  (customerToken: CustomerToken, cartId: string|number): Promise<RequestResponse>
+}
+interface DeleteCall {
+  (customerToken: CustomerToken, cartId: string|number, cartItem: any): Promise<RequestResponse>
+}
+interface PullCall {
+  (customerToken: CustomerToken, cartId: string|number): Promise<RequestResponse>
+}
+interface TotalsCall {
+  (customerToken: CustomerToken, cartId: string|number): Promise<RequestResponse>
+}
+interface ShippingInformationCall {
+  (customerToken: CustomerToken, cartId: string|number, body: any): Promise<RequestResponse>
+}
+interface ShippingMethodsCall {
+  (customerToken: CustomerToken, cartId: string|number, address: any): Promise<RequestResponse>
+}
+interface PaymentMethodsCall {
+  (customerToken: CustomerToken, cartId: string|number): Promise<RequestResponse>
+}
+interface GetCouponCall {
+  (customerToken: CustomerToken, cartId: string|number): Promise<RequestResponse>
+}
+
+
+export interface CartModule {
+  create: CreateCall
+  update: UpdateCall
+  applyCoupon: ApplyCouponCall
+  deleteCoupon: DeleteCouponCall
+  delete: DeleteCall
+  pull: PullCall
+  totals: TotalsCall
+  shippingInformation: ShippingInformationCall
+  shippingMethods: ShippingMethodsCall
+  paymentMethods: PaymentMethodsCall
+  getCoupon: GetCouponCall
+}
+
+export default function (restClient: RestClientInstance): CartModule {
+  let url = 'cart/';
+
+  const createCall: CreateCall = (customerToken: CustomerToken) => {
+    url += `create?token=${customerToken}`;
+    return restClient.post(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const updateCall: UpdateCall = (customerToken: CustomerToken, cartId: string|number, cartItem: any) => {
+    url += `update?token=${customerToken}&cartId=${cartId}`;
+    return restClient.post(url, { cartItem: cartItem }).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const applyCouponCall: ApplyCouponCall = (customerToken: CustomerToken, cartId: string|number, coupon: string) => {
+    url += `applyCoupon?token=${customerToken}&cartId=${cartId}&coupon=${coupon}`;
+    return restClient.post(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const deleteCouponCall: DeleteCouponCall = (customerToken: CustomerToken, cartId: string|number) => {
+    url += `deleteCoupon?token=${customerToken}&cartId=${cartId}`;
+    return restClient.post(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const deleteCall: DeleteCall = (customerToken: CustomerToken, cartId: string|number, cartItem: any) => {
+    url += `delete?token=${customerToken}&cartId=${cartId}`;
+    return restClient.post(url, { cartItem: cartItem }).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const pullCall: PullCall = (customerToken: CustomerToken, cartId: string|number) => {
+    url += `pull?token=${customerToken}&cartId=${cartId}`;
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const totalsCall: TotalsCall = (customerToken: CustomerToken, cartId: string|number) => {
+    url += `totals?token=${customerToken}&cartId=${cartId}`;
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const shippingInformationCall: ShippingInformationCall = (customerToken: CustomerToken, cartId: string|number, body) => {
+    url += `totals?token=${customerToken}&cartId=${cartId}`;
+    return restClient.post(url, body).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const shippingMethodsCall: ShippingMethodsCall = (customerToken: CustomerToken, cartId: string|number, address) => {
+    url += `shippingMethods?token=${customerToken}&cartId=${cartId}`;
+    return restClient.post(url, { address: address }).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const paymentMethodsCall: PaymentMethodsCall = (customerToken: CustomerToken, cartId: string|number) => {
+    url += `paymentMethods?token=${customerToken}&cartId=${cartId}`;
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const getCouponCall: GetCouponCall = (customerToken: CustomerToken, cartId: string|number) => {
+    url += `coupon?token=${customerToken}&cartId=${cartId}`;
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  return {
+    create: createCall,
+    update: updateCall,
+    applyCoupon: applyCouponCall,
+    deleteCoupon: deleteCouponCall,
+    delete: deleteCall,
+    pull: pullCall,
+    totals: totalsCall,
+    shippingInformation: shippingInformationCall,
+    shippingMethods: shippingMethodsCall,
+    paymentMethods: paymentMethodsCall,
+    getCoupon: getCouponCall,
+  };
+}
diff --git a/lib/contact.js b/lib/contact.js
deleted file mode 100644
index 996698e..0000000
--- a/lib/contact.js
+++ /dev/null
@@ -1,18 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'contact/';
-  let url = urlPrefix;
-  function getResponse(data){
-    if(data.code === 200){
-      return data.result;
-    }
-    return false;
-  }
-  module.submit = (form) => {
-    url += `submit`;
-    return restClient.post(url, {form}).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  return module;
-};
diff --git a/lib/contact.ts b/lib/contact.ts
new file mode 100644
index 0000000..e215964
--- /dev/null
+++ b/lib/contact.ts
@@ -0,0 +1,24 @@
+import { getResponse, RequestResponse } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface SubmitCall {
+  (form): Promise<RequestResponse>
+}
+
+export interface ContactModule {
+  submit: SubmitCall
+}
+
+export default function (restClient: RestClientInstance): ContactModule {
+  let url = 'contact/';
+
+  const submitCall: SubmitCall = (form) => {
+    url += `submit`;
+    return restClient.post(url, {form}).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  return {
+    submit: submitCall
+  };
+};
diff --git a/lib/helper.ts b/lib/helper.ts
new file mode 100644
index 0000000..a3902de
--- /dev/null
+++ b/lib/helper.ts
@@ -0,0 +1,13 @@
+export type RequestResponse = any|boolean
+export type CustomerToken = string
+
+export function getResponse(data: any): RequestResponse {
+  if(isResponseValid(data)){
+    return data.result;
+  }
+  return false;
+}
+
+export function isResponseValid(data: any): boolean {
+  return data.code === 200;
+}
diff --git a/lib/log.js b/lib/log.ts
similarity index 93%
rename from lib/log.js
rename to lib/log.ts
index 50c6520..e16ac1f 100644
--- a/lib/log.js
+++ b/lib/log.ts
@@ -16,4 +16,4 @@ var logger = new winston.Logger({
 
 logger.info('Winston logging library initialized.');
 
-module.exports = logger;
+export default logger;
diff --git a/lib/newsletter.js b/lib/newsletter.js
deleted file mode 100644
index 9c1396e..0000000
--- a/lib/newsletter.js
+++ /dev/null
@@ -1,24 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'newsletter/';
-  let url = urlPrefix;
-  function getResponse(data){
-    if(data.code === 200){
-      return data.result;
-    }
-    return false;
-  }
-  module.subscribe = (emailAddress) => {
-    url += `subscribe`;
-    return restClient.post(url, {emailAddress: emailAddress}).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  module.unsubscribe = (customerToken) => {
-    url += `unsubscribe?token=${customerToken}`;
-    return restClient.post(url).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  return module;
-};
diff --git a/lib/newsletter.ts b/lib/newsletter.ts
new file mode 100644
index 0000000..30649fb
--- /dev/null
+++ b/lib/newsletter.ts
@@ -0,0 +1,35 @@
+import { getResponse, RequestResponse, CustomerToken } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface SubscribeCall {
+  (emailAddress: string): Promise<RequestResponse>
+}
+interface UnsubscribeCall {
+  (customerToken: CustomerToken): Promise<RequestResponse>
+}
+
+
+export interface NewsletterModule {
+  subscribe: SubscribeCall,
+  unsubscribe: UnsubscribeCall
+}
+
+export default function (restClient: RestClientInstance): NewsletterModule {
+  let url = 'newsletter/';
+  const subscribeCall: SubscribeCall = (emailAddress) => {
+    url += `subscribe`;
+    return restClient.post(url, {emailAddress: emailAddress}).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  const unsubscribeCall: UnsubscribeCall = (customerToken) => {
+    url += `unsubscribe?token=${customerToken}`;
+    return restClient.post(url).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  return {
+    subscribe: subscribeCall,
+    unsubscribe: unsubscribeCall
+  };
+};
diff --git a/lib/order.js b/lib/order.js
deleted file mode 100644
index 023831a..0000000
--- a/lib/order.js
+++ /dev/null
@@ -1,28 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'order/';
-  let url = urlPrefix;
-  function isResponseValid(data) {
-    return data.code === 200;
-  }
-  function getResponse(data){
-    if(isResponseValid(data)){
-      return data.result;
-    }
-    return false;
-  }
-  module.create = (orderData) => {
-    url += `create`;
-    return restClient.post(url, orderData).then((data)=> {
-      if (isResponseValid(data)) {
-        data.result = {
-          magentoOrderId: data.result,
-          backendOrderId: data.result,
-          transferedAt: new Date()
-        };
-      }
-      return getResponse(data);
-    });
-  }
-  return module;
-}
diff --git a/lib/order.ts b/lib/order.ts
new file mode 100644
index 0000000..535536c
--- /dev/null
+++ b/lib/order.ts
@@ -0,0 +1,31 @@
+import { getResponse, isResponseValid, RequestResponse } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface CreateCall {
+  (oderData: any): Promise<RequestResponse>
+}
+
+export interface OrderModule {
+  create: CreateCall
+}
+
+export default function (restClient: RestClientInstance): OrderModule {
+  let url = 'order/';
+
+   const createCall:CreateCall  = (orderData) => {
+    url += `create`;
+    return restClient.post(url, orderData).then((data)=> {
+      if (isResponseValid(data)) {
+        data.result = {
+          magentoOrderId: data.result,
+          backendOrderId: data.result,
+          transferedAt: new Date()
+        };
+      }
+      return getResponse(data);
+    });
+  }
+  return {
+    create: createCall
+  };
+}
diff --git a/lib/rest_client.js b/lib/rest_client.js
deleted file mode 100644
index 6db954c..0000000
--- a/lib/rest_client.js
+++ /dev/null
@@ -1,138 +0,0 @@
-'use strict';
-
-const OAuth = require('oauth-1.0a');
-const request = require('request');
-const logger = require('./log');
-
-module.exports.RestClient = function (options) {
-  let instance = {};
-
-  var servelrUrl = options.url;
-  var oauth = OAuth({
-    consumer: {
-      public: options.consumerKey,
-      secret: options.consumerSecret
-    },
-    signature_method: 'HMAC-SHA1'
-  });
-  var token = {
-    public: options.accessToken,
-    secret: options.accessTokenSecret
-  };
-
-  function apiCall(request_data, request_token = '') {
-    logger.debug('Calling API endpoint: ' + request_data.method + ' ' + request_data.url + ' token: ' + request_token);
-
-    logger.info({
-      url: request_data.url,
-      method: request_data.method,
-      headers: request_token ? { 'Authorization': 'Bearer ' + request_token } : oauth.toHeader(oauth.authorize(request_data, token)),
-      json: true,
-      body: request_data.body,
-    });
-    /* eslint no-undef: off*/
-    return new Promise(function (resolve, reject) {
-      request({
-        url: request_data.url,
-        method: request_data.method,
-        headers: request_token ? { 'Authorization': 'Bearer ' + request_token } : oauth.toHeader(oauth.authorize(request_data, token)),
-        json: true,
-        body: request_data.body,
-      }, function (error, response, body) {
-        logger.debug('Response received')
-        if (error) {
-          logger.error('Error occured: ' + error);
-          reject(error);
-          return;
-        } else if (!httpCallSucceeded(response)) {
-          let errorMessage = ''
-
-          if (body) {
-            errorMessage = 'HTTP ERROR ' + body.code;
-          } else {
-            errorMessage = 'HTTP ERROR ' + response.code;
-          }
-
-          if (body && body.hasOwnProperty('result'))
-            errorMessage = errorString(body.result, body.hasOwnProperty('parameters') ? body.parameters : {});
-
-          logger.error('API call failed: ' + errorMessage);
-          reject(errorMessage);
-        }
-        resolve(body);
-      });
-    });
-  }
-
-  instance.consumerToken = function (login_data) {
-    return apiCall({
-      url: createUrl('/integration/customer/token'),
-      method: 'POST',
-      body: login_data
-    })
-  }
-
-  function httpCallSucceeded(response) {
-    return response.statusCode >= 200 && response.statusCode < 300;
-  }
-
-  function errorString(message, parameters) {
-    if (parameters === null) {
-      return message;
-    }
-    let parameterPlaceholder
-    if (parameters instanceof Array) {
-      for (let i = 0; i < parameters.length; i++) {
-        parameterPlaceholder = '%' + (i + 1).toString();
-        message = message.replace(parameterPlaceholder, parameters[i]);
-      }
-    } else if (parameters instanceof Object) {
-      for (let key in parameters) {
-        parameterPlaceholder = '%' + key;
-        message = message.replace(parameterPlaceholder, parameters[key]);
-      }
-    }
-
-    return message;
-  }
-
-  instance.get = function (resourceUrl, request_token = '') {
-    const request_data = {
-      url: createUrl(resourceUrl),
-      method: 'GET'
-    };
-    return apiCall(request_data, request_token);
-  }
-
-  function createUrl(resourceUrl) {
-    return servelrUrl + '/' + resourceUrl;
-  }
-
-  instance.post = function (resourceUrl, data, request_token = '') {
-    const request_data = {
-      url: createUrl(resourceUrl),
-      method: 'POST',
-      body: data
-    };
-    return apiCall(request_data, request_token);
-  }
-
-  instance.put = function (resourceUrl, data, request_token = '') {
-    const request_data = {
-      url: createUrl(resourceUrl),
-      method: 'PUT',
-      body: data
-    };
-    return apiCall(request_data, request_token);
-  }
-
-  instance.delete = function (resourceUrl, request_token = '') {
-    const request_data = {
-      url: createUrl(resourceUrl),
-      method: 'DELETE'
-    };
-    return apiCall(request_data, request_token);
-  }
-
-  return instance;
-}
diff --git a/lib/rest_client.ts b/lib/rest_client.ts
new file mode 100644
index 0000000..a55d7f9
--- /dev/null
+++ b/lib/rest_client.ts
@@ -0,0 +1,195 @@
+'use strict';
+
+import logger from "./log";
+
+const OAuth = require('oauth-1.0a');
+const request = require('request');
+
+export interface RestClientOptions {
+  version: string
+  url: string
+  consumerKey?: string
+  consumerSecret?: string
+  accessToken?: string
+  accessTokenSecret?: string
+  basicAuth?: {
+    user?: string
+    password?: string
+    enabled: boolean
+  }
+}
+
+type RequestToken = string
+
+interface GetCall {
+  (resourceUrl: string, request_token?: RequestToken): Promise<any>
+}
+interface PostCall {
+  (resourceUrl: string,data?: any, request_token?: RequestToken): Promise<any>
+}
+interface PutCall {
+  (resourceUrl: string,data?: any, request_token?: RequestToken): Promise<any>
+}
+interface DeleteCall {
+  (resourceUrl: string, request_token?: RequestToken): Promise<any>
+}
+
+interface RequestData {
+  url: string
+  method: string,
+  body?: any
+}
+
+export interface RestClientInstance {
+  consumerToken: (login_data: any) => any
+  get: GetCall
+  post: PostCall
+  put: PutCall
+  delete: DeleteCall
+}
+
+export const RestClient = function (options: RestClientOptions): RestClientInstance {
+
+  const serverUrl = options.url;
+  let oauth = OAuth({
+    consumer: {
+      public: options.consumerKey,
+      secret: options.consumerSecret
+    },
+    signature_method: 'HMAC-SHA1'
+  });
+  let token = {
+    public: options.accessToken,
+    secret: options.accessTokenSecret
+  };
+
+  function apiCall(request_data: RequestData, request_token: RequestToken ='') {
+    logger.debug('Calling API endpoint: ' + request_data.method + ' ' + request_data.url + ' token: ' + request_token);
+
+    let requestParameter: Record<string, any> = {
+      url: request_data.url,
+      method: request_data.method,
+      json: true,
+      body: request_data.body,
+    }
+
+    if (options.basicAuth?.enabled) {
+      const { password, user } = options.basicAuth
+      if (password && user) {
+        requestParameter.auth = {
+          user: user,
+          pass: password,
+          sendImmediately: false
+        }
+      }
+    } else {
+      requestParameter.headers = request_token ? { 'Authorization': 'Bearer ' + request_token } : oauth.toHeader(oauth.authorize(request_data, token))
+    }
+
+    logger.info(requestParameter);
+    /* eslint no-undef: off*/
+    return new Promise(function (resolve, reject) {
+      request(requestParameter, function (error, response, body) {
+        logger.debug('Response received')
+        if (error) {
+          logger.error('Error occured: ' + error);
+          reject(error);
+          return;
+        } else if (!httpCallSucceeded(response)) {
+          let errorMessage = ''
+
+          if (body) {
+            errorMessage = 'HTTP ERROR ' + body.code;
+          } else {
+            errorMessage = 'HTTP ERROR ' + response.code;
+          }
+
+          if (body && body.hasOwnProperty('result'))
+            errorMessage = errorString(body.result, body.hasOwnProperty('parameters') ? body.parameters : {});
+
+          logger.error('API call failed: ' + errorMessage);
+          reject(errorMessage);
+        }
+        resolve(body);
+      });
+    });
+  }
+
+  const consumerToken = (login_data: any) => {
+    return apiCall({
+      url: createUrl('/integration/customer/token'),
+      method: 'POST',
+      body: login_data
+    })
+  }
+
+  const getCall: GetCall = (resourceUrl, request_token: RequestToken ='') => {
+    const request_data: RequestData = {
+      url: createUrl(resourceUrl),
+      method: 'GET'
+    };
+    return apiCall(request_data, request_token);
+  }
+
+  const postCall: PostCall = (resourceUrl, data, request_token: RequestToken ='') => {
+    const request_data: RequestData = {
+      url: createUrl(resourceUrl),
+      method: 'POST',
+      body: data
+    };
+    return apiCall(request_data, request_token);
+  }
+
+  const putCall: PutCall = (resourceUrl, data, request_token: RequestToken ='') => {
+    const request_data: RequestData = {
+      url: createUrl(resourceUrl),
+      method: 'PUT',
+      body: data
+    };
+    return apiCall(request_data, request_token);
+  }
+
+  const deleteCall: DeleteCall = (resourceUrl, request_token: RequestToken ='') => {
+    const request_data: RequestData = {
+      url: createUrl(resourceUrl),
+      method: 'DELETE'
+    };
+    return apiCall(request_data, request_token);
+  }
+
+  function httpCallSucceeded(response: any) {
+    return response.statusCode >= 200 && response.statusCode < 300;
+  }
+
+  function errorString(message: string, parameters: null|Array<any>|object): string {
+    if (parameters === null) {
+      return message;
+    }
+    let parameterPlaceholder
+    if (parameters instanceof Array) {
+      for (let i = 0; i < parameters.length; i++) {
+        parameterPlaceholder = '%' + (i + 1).toString();
+        message = message.replace(parameterPlaceholder, parameters[i]);
+      }
+    } else if (parameters instanceof Object) {
+      for (let key in parameters) {
+        parameterPlaceholder = '%' + key;
+        message = message.replace(parameterPlaceholder, parameters[key]);
+      }
+    }
+
+    return message;
+  }
+
+  function createUrl(resourceUrl: string) {
+    return serverUrl + '/' + resourceUrl;
+  }
+
+  return {
+    consumerToken,
+    get: getCall,
+    post: postCall,
+    put: putCall,
+    delete: deleteCall
+  };
+}
diff --git a/lib/stock.js b/lib/stock.js
deleted file mode 100644
index 8cd3e95..0000000
--- a/lib/stock.js
+++ /dev/null
@@ -1,18 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'stock/';
-  let url = urlPrefix;
-  function getResponse(data){
-    if(data.code === 200){
-      return data.result;
-    }
-    return false;
-  }
-  module.check = (sku) => {
-    url += `check?sku=${sku}`;
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  return module;
-};
diff --git a/lib/stock.ts b/lib/stock.ts
new file mode 100644
index 0000000..ca606e3
--- /dev/null
+++ b/lib/stock.ts
@@ -0,0 +1,30 @@
+import { RequestResponse } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface CeckCall {
+  (sku: string|number): Promise<RequestResponse>
+}
+
+export interface StockModule {
+  check: CeckCall
+}
+
+export default function (restClient: RestClientInstance): StockModule {
+  const urlPrefix = 'stock/';
+  let url = urlPrefix;
+  function getResponse(data){
+    if(data.code === 200){
+      return data.result;
+    }
+    return false;
+  }
+  const checkCall: CeckCall = (sku) => {
+    url += `check?sku=${sku}`;
+    return restClient.get(url).then((data) => {
+      return getResponse(data);
+    });
+  };
+  return {
+    check: checkCall
+  };
+};
diff --git a/lib/stock_alert.js b/lib/stock_alert.js
deleted file mode 100644
index 1168ac9..0000000
--- a/lib/stock_alert.js
+++ /dev/null
@@ -1,32 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'stockalert/';
-  let url = urlPrefix;
-  function getResponse(data){
-    if (data.code === 200){
-      return data.result;
-    }
-
-    return false;
-  }
-  module.subscribe = (customerToken, productId, emailAddress) => {
-    url += `add`;
-
-    if (typeof customerToken !== 'undefined' && customerToken) {
-      url += `?token=${customerToken}`
-    }
-
-    let alertData = {
-      productId: productId
-    }
-
-    if (emailAddress) {
-      alertData.emailAddress = emailAddress
-    }
-
-    return restClient.post(url, alertData).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  return module;
-};
diff --git a/lib/stock_alert.ts b/lib/stock_alert.ts
new file mode 100644
index 0000000..df3bfe9
--- /dev/null
+++ b/lib/stock_alert.ts
@@ -0,0 +1,42 @@
+import { getResponse, RequestResponse, CustomerToken } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface SubscribeCall {
+  (customerToken: CustomerToken|undefined, productId: string|number, emailAddress?: string): Promise<RequestResponse>
+}
+
+interface AlertData {
+  productId: string|number
+  emailAddress?: string
+}
+
+export interface StockAlertModule {
+  subscribe: SubscribeCall
+}
+
+export default function (restClient: RestClientInstance): StockAlertModule {
+  let url = 'stockalert/';
+
+  const subscribeCall: SubscribeCall = (customerToken = undefined, productId, emailAddress) => {
+    url += `add`;
+
+    if (typeof customerToken !== 'undefined' && customerToken) {
+      url += `?token=${customerToken}`
+    }
+
+    let alertData: AlertData = {
+      productId: productId
+    }
+
+    if (emailAddress) {
+      alertData.emailAddress = emailAddress
+    }
+
+    return restClient.post(url, alertData).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  return {
+    subscribe: subscribeCall
+  };
+};
diff --git a/lib/user.js b/lib/user.js
deleted file mode 100644
index 2dc8e2c..0000000
--- a/lib/user.js
+++ /dev/null
@@ -1,68 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  let url = 'user/';
-  function getResponse(data){
-    if (data.code === 200){
-      return data.result;
-    }
-
-    return false;
-  }
-  module.login = (userData) => {
-    url += 'login';
-    return restClient.post(url, userData).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.resetPassword = function (emailData) {
-    url += `resetPassword`;
-    return restClient.post(url, {email: emailData.email}).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.changePassword = function (passwordData) {
-    url += `changePassword?token=${passwordData.token}`;
-    return restClient.post(url, passwordData.body).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.create = function (userData) {
-    url += `create`;
-    return restClient.post(url, userData).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.creditValue = function (customerToken) {
-    const getCreditUrl = `user_credit/get?token=${customerToken}`
-
-    return restClient.get(getCreditUrl).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.refillCredit = function (customerToken, creditCode) {
-    const getCreditUrl = `user_credit/refill?token=${customerToken}`
-
-    return restClient.post(getCreditUrl, {credit_code: creditCode}).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.orderHistory = function (customerToken, page, pageSize) {
-    url += `orderHistory?token=${customerToken}`;
-    return restClient.get(url, {page: page, pageSize: pageSize}).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.update = function (userData) {
-    url += `me?token=${userData.token}`
-    return restClient.post(url, userData.body).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  module.me = function (customerToken) {
-    const url = `user/me?token=${customerToken}`
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  }
-  return module;
-}
diff --git a/lib/user.ts b/lib/user.ts
new file mode 100644
index 0000000..b85a9b7
--- /dev/null
+++ b/lib/user.ts
@@ -0,0 +1,131 @@
+import { getResponse, RequestResponse, CustomerToken } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface EmailData {
+  email: string
+}
+interface PasswordData {
+  token: string
+  body: string
+}
+
+interface LoginCall {
+  (userData: any): Promise<RequestResponse>
+}
+interface ResetPasswordCall {
+  (emailData: EmailData): Promise<RequestResponse>
+}
+interface ChangePasswordCall {
+  (passwordData: PasswordData): Promise<RequestResponse>
+}
+interface CreateCall {
+  (userData: any): Promise<RequestResponse>
+}
+interface CreditValueCall {
+  (customerToken: CustomerToken): Promise<RequestResponse>
+}
+interface RefillCreditCall {
+  (customerToken: CustomerToken, creditCode: string|any): Promise<RequestResponse>
+}
+interface OrderHistoryCall {
+  (customerToken: CustomerToken, page?: string|number, pageSize?: string|number): Promise<RequestResponse>
+}
+interface UpdateCall {
+  (userData: any): Promise<RequestResponse>
+}
+interface MeCall {
+  (customerToken: CustomerToken): Promise<RequestResponse>
+}
+
+export interface UserModule {
+  login :LoginCall
+  resetPassword :ResetPasswordCall
+  changePassword :ChangePasswordCall
+  create :CreateCall
+  creditValue :CreditValueCall
+  refillCredit :RefillCreditCall
+  orderHistory :OrderHistoryCall
+  update :UpdateCall
+  me :MeCall
+}
+
+export default function (restClient: RestClientInstance): UserModule {
+  let url = 'user/';
+
+  const loginCall: LoginCall = function (userData) {
+    url += 'login';
+    return restClient.post(url, userData).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const resetPasswordCall: ResetPasswordCall = function (emailData) {
+    url += `resetPassword`;
+    return restClient.post(url, {email: emailData.email}).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const changePasswordCall: ChangePasswordCall = function (passwordData) {
+    url += `changePassword?token=${passwordData.token}`;
+    return restClient.post(url, passwordData.body).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const createCall: CreateCall = function (userData) {
+    url += `create`;
+    return restClient.post(url, userData).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const creditValueCall: CreditValueCall = function (customerToken) {
+    const getCreditUrl = `user_credit/get?token=${customerToken}`
+
+    return restClient.get(getCreditUrl).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const refillCreditCall: RefillCreditCall = function (customerToken, creditCode) {
+    const getCreditUrl = `user_credit/refill?token=${customerToken}`
+
+    return restClient.post(getCreditUrl, {credit_code: creditCode}).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const orderHistoryCall: OrderHistoryCall = function (customerToken, page, pageSize) {
+    url += `orderHistory?token=${customerToken}`;
+
+    if (page) {
+      url += `&page=${page}`
+    }
+
+    if (pageSize) {
+      url += `&pageSize=${pageSize}`
+    }
+
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const updateCall: UpdateCall = function (userData) {
+    url += `me?token=${userData.token}`
+    return restClient.post(url, userData.body).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  const meCall: MeCall = function (customerToken) {
+    const url = `user/me?token=${customerToken}`
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  }
+  return {
+    login: loginCall,
+    resetPassword: resetPasswordCall,
+    changePassword: changePasswordCall,
+    create: createCall,
+    creditValue: creditValueCall,
+    refillCredit: refillCreditCall,
+    orderHistory: orderHistoryCall,
+    update: updateCall,
+    me: meCall,
+  };
+}
diff --git a/lib/wishlist.js b/lib/wishlist.js
deleted file mode 100644
index 50992a0..0000000
--- a/lib/wishlist.js
+++ /dev/null
@@ -1,36 +0,0 @@
-module.exports = function (restClient) {
-  let module = {};
-  const urlPrefix = 'wishlist/';
-  let url = urlPrefix;
-  function getResponse(data){
-    if(data.code === 200){
-      return data.result;
-    }
-    return false;
-  }
-  module.pull = (customerToken) => {
-    url += `pull?token=${customerToken}`;
-    return restClient.get(url).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  module.update = (customerToken, wishListItem) => {
-    url += `update?token=${customerToken}`;
-    return restClient.post(url, {wishListItem: wishListItem}).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  module.delete = (customerToken, wishListItem) => {
-    url += `delete?token=${customerToken}`;
-    return restClient.post(url, {wishListItem: wishListItem}).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  module.moveToCart = (customerToken, cartId, wishListItem) => {
-    url += `moveToCart?token=${customerToken}&cartId=${cartId}`;
-    return restClient.post(url, {wishListItem: wishListItem}).then((data)=> {
-      return getResponse(data);
-    });
-  };
-  return module;
-};
diff --git a/lib/wishlist.ts b/lib/wishlist.ts
new file mode 100644
index 0000000..158513d
--- /dev/null
+++ b/lib/wishlist.ts
@@ -0,0 +1,60 @@
+import { getResponse, RequestResponse, CustomerToken } from "./helper";
+import { RestClientInstance } from "./rest_client";
+
+interface PullCall {
+  (customerToken: CustomerToken): Promise<RequestResponse>
+}
+
+interface UpdateCall {
+  (customerToken: CustomerToken, wishListItem): Promise<RequestResponse>
+}
+
+interface DeleteCall {
+  (customerToken: CustomerToken, wishListItem): Promise<RequestResponse>
+}
+
+interface MoveToCartCall {
+  (customerToken: CustomerToken, cartId: string|number, wishListItem: any): Promise<RequestResponse>
+}
+
+export interface WishlistModule {
+  pull: PullCall
+  update: UpdateCall
+  delete: DeleteCall
+  moveToCart: MoveToCartCall
+}
+
+export default function (restClient: RestClientInstance): WishlistModule {
+  let url = 'wishlist/';
+
+  const pullCall: PullCall = (customerToken) => {
+    url += `pull?token=${customerToken}`;
+    return restClient.get(url).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  const updateCall: UpdateCall = (customerToken, wishListItem) => {
+    url += `update?token=${customerToken}`;
+    return restClient.post(url, {wishListItem: wishListItem}).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  const deleteCall: DeleteCall = (customerToken, wishListItem) => {
+    url += `delete?token=${customerToken}`;
+    return restClient.post(url, {wishListItem: wishListItem}).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  const moveToCartCall: MoveToCartCall = (customerToken, cartId, wishListItem) => {
+    url += `moveToCart?token=${customerToken}&cartId=${cartId}`;
+    return restClient.post(url, {wishListItem: wishListItem}).then((data)=> {
+      return getResponse(data);
+    });
+  };
+  return {
+    pull: pullCall,
+    update: updateCall,
+    delete: deleteCall,
+    moveToCart: moveToCartCall,
+  };
+};
diff --git a/package.json b/package.json
index 2859e3f..0cb648d 100644
--- a/package.json
+++ b/package.json
@@ -4,6 +4,11 @@
   "version": "0.1.0",
   "license": "MIT",
   "deprecated": false,
+  "scripts": {
+    "build": "tsc --build",
+    "prepublishOnly": "npm run build",
+    "prebuild": "rimraf \"lib/*.{d.ts,js}\" \"index.{d.ts,js}\""
+  },
   "dependencies": {
     "oauth-1.0a": "^1.0.1",
     "request": "^2.72.0",
@@ -12,6 +17,12 @@
   "directories": {
     "lib": "./lib"
   },
+  "files": [
+    "lib/*.d.ts",
+    "index.d.ts",
+    "lib/*.js",
+    "index.js"
+  ],
   "homepage": "https://github.com/DivanteLtd/magento1-vsbridge-client",
   "keywords": [
     "magento1",
@@ -19,5 +30,11 @@
     "VsBridge",
     "API"
   ],
-  "main": "index.js"
+  "main": "index.js",
+  "devDependencies": {
+    "@types/node": "^13.13.5",
+    "@types/request": "^2.48.4",
+    "rimraf": "^3.0.2",
+    "typescript": "3.8.*"
+  }
 }
diff --git a/tsconfig.json b/tsconfig.json
new file mode 100644
index 0000000..c024785
--- /dev/null
+++ b/tsconfig.json
@@ -0,0 +1,23 @@
+{
+  "compilerOptions": {
+    "target": "es2017",
+    "declaration": true,
+    "strict": false,
+    "allowJs": false,
+    "importHelpers": false,
+    "module": "commonjs",
+    "experimentalDecorators": true,
+    "emitDecoratorMetadata": true,
+    "esModuleInterop": true,
+    "resolveJsonModule": true,
+    "noLib": false,
+    "skipLibCheck": true,
+    "sourceMap": false,
+    "baseUrl": ".",
+    "lib": ["es7"]
+  },
+  "include": [
+    "lib/**/*",
+    "index.ts"
+  ]
+}