diff --git a/index.d.ts b/index.d.ts
new file mode 100644
index 0000000..641b7aa
--- /dev/null
+++ b/index.d.ts
@@ -0,0 +1,107 @@
+declare module 'sslcommerz-lts' {
+    export interface SSLCommerzInitData {
+        total_amount: number | string;
+        currency: string;
+        tran_id: string;
+        success_url: string;
+        fail_url: string;
+        cancel_url: string;
+        ipn_url?: string;
+        multi_card_name?: string;
+        allowed_bin?: string;
+        emi_option?: string;
+        emi_max_inst_option?: string;
+        emi_selected_inst?: string;
+        cus_name: string;
+        cus_email: string;
+        cus_add1: string;
+        cus_add2?: string;
+        cus_city: string;
+        cus_state?: string;
+        cus_postcode: string | number;
+        cus_country: string;
+        cus_phone: string;
+        cus_fax?: string;
+        shipping_method: string;
+        num_of_item?: number | string;
+        ship_name?: string;
+        ship_add1?: string;
+        ship_add2?: string;
+        ship_city?: string;
+        ship_state?: string;
+        ship_postcode?: string | number;
+        ship_country?: string;
+        product_name: string;
+        product_category: string;
+        product_profile: string;
+        hours_till_departure?: string;
+        flight_type?: string;
+        pnr?: string;
+        journey_from_to?: string;
+        third_party_booking?: string;
+        hotel_name?: string;
+        length_of_stay?: string;
+        check_in_time?: string;
+        hotel_city?: string;
+        product_type?: string;
+        topup_number?: string;
+        country_topup?: string;
+        cart?: string;
+        product_amount?: string;
+        discount_amount?: string;
+        convenience_fee?: string;
+        value_a?: string;
+        value_b?: string;
+        value_c?: string;
+        value_d?: string;
+        [key: string]: any;
+    }
+
+    export interface SSLCommerzValidateData {
+        val_id: string;
+    }
+
+    export interface SSLCommerzRefundData {
+        refund_amount: number | string;
+        refund_remarks: string;
+        bank_tran_id: string;
+        refe_id: string;
+    }
+
+    export interface SSLCommerzRefundQueryData {
+        refund_ref_id: string;
+    }
+
+    export interface SSLCommerzTransQueryBySessionData {
+        sessionkey: string;
+    }
+
+    export interface SSLCommerzTransQueryByTransData {
+        tran_id: string;
+    }
+
+    export interface SSLCommerzApiResponse {
+        status: string;
+        failedreason: string;
+        sessionkey: string;
+        gw: { [key: string]: string };
+        redirectGatewayURL: string;
+        directPaymentURL: string;
+        GatewayPageURL: string;
+        storeBanner: string;
+        storeLogo: string;
+        desc: any[];
+        is_direct_pay_enable: string;
+        [key: string]: any;
+    }
+
+    export default class SSLCommerzPayment {
+        constructor(store_id: string, store_passwd: string, live?: boolean);
+        init(data: SSLCommerzInitData, url?: string | boolean, method?: string): Promise<SSLCommerzApiResponse>;
+        validate(data: SSLCommerzValidateData, url?: string | boolean, method?: string): Promise<any>;
+        initiateRefund(data: SSLCommerzRefundData, url?: string | boolean, method?: string): Promise<any>;
+        refundQuery(data: SSLCommerzRefundQueryData, url?: string | boolean, method?: string): Promise<any>;
+        transactionQueryBySessionId(data: SSLCommerzTransQueryBySessionData, url?: string | boolean, method?: string): Promise<any>;
+        transactionQueryByTransactionId(data: SSLCommerzTransQueryByTransData, url?: string | boolean, method?: string): Promise<any>;
+    }
+}
diff --git a/package.json b/package.json
index 20e64dc..96a4979 100644
--- a/package.json
+++ b/package.json
@@ -3,6 +3,7 @@
   "description": "LTS package, Officially supported by SSLCommerz Integration Team.",
   "version": "1.2.0",
   "main": "index.js",
+  "types": "index.d.ts",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
diff --git a/readme.md b/readme.md
index 5cb090c..c6426af 100755
--- a/readme.md
+++ b/readme.md
@@ -76,7 +76,7 @@ app.listen(port, () => {
 
 app.get('/validate', (req, res) => {
     const data = {
-        val_id:ADGAHHGDAKJ456454 //that you go from sslcommerz response
+        val_id: 'ADGAHHGDAKJ456454' //that you got from sslcommerz response
     };
     const sslcz = new SSLCommerzPayment(store_id, store_passwd, is_live)
     sslcz.validate(data).then(data => {
@@ -92,10 +92,10 @@ app.get('/validate', (req, res) => {
 
 app.get('/initiate-refund', (req, res) => {
     const data = {
-        refund_amount:10,
-        refund_remarks:'',
-        bank_tran_id:CB5464321445456456,
-        refe_id:EASY5645415455,
+        refund_amount: 10,
+        refund_remarks: '',
+        bank_tran_id: 'CB5464321445456456',
+        refe_id: 'EASY5645415455',
     };
     const sslcz = new SSLCommerzPayment(store_id, store_passwd, is_live)
     sslcz.initiateRefund(data).then(data => {
@@ -111,7 +111,7 @@ app.get('/initiate-refund', (req, res) => {
 
 app.get('/refund-query', (req, res) => {
     const data = {
-        refund_ref_id:SL4561445410,
+        refund_ref_id: 'SL4561445410',
     };
     const sslcz = new SSLCommerzPayment(store_id, store_passwd, is_live)
     sslcz.refundQuery(data).then(data => {
@@ -127,7 +127,7 @@ app.get('/refund-query', (req, res) => {
 //you also use this as internal method
 app.get('/transaction-query-by-transaction-id', (req, res) => {
     const data = {
-        tran_id:AKHLAKJS5456454,
+        tran_id: 'AKHLAKJS5456454',
     };
     const sslcz = new SSLCommerzPayment(store_id, store_passwd, is_live)
     sslcz.transactionQueryByTransactionId(data).then(data => {
@@ -143,7 +143,7 @@ app.get('/transaction-query-by-transaction-id', (req, res) => {
 //you also use this as internal method
 app.get('/transaction-query-by-session-id', (req, res) => {
     const data = {
-        sessionkey:AKHLAKJS5456454,
+        sessionkey: 'AKHLAKJS5456454',
     };
     const sslcz = new SSLCommerzPayment(store_id, store_passwd, is_live)
     sslcz.transactionQueryBySessionId(data).then(data => {