Paytm wallets are used in almost all the websites we encounter these days. Also it is one of the best wallet used for handling digital transactions.

Although Paytm has provided us with the direct API for checking balance and making payments if we have sufficient balance in our wallet. But what if we do not have sufficient balance and we wanted to add money to our wallet from the current website.

So let us now look into how we can handle this use case for adding money to our Paytm wallet directly from the currently open website using javascript in backend and frontend.

This is done by handling redirection to the Paytm website from our current website. To do so we need to post a form to :

Staging:

https://pguat.paytm.com/oltp-web/processTransaction

Production:

https://secure.paytm.in/oltp-web/processTransaction

For this form we need the following parameters to our form:

As we can see, the checksum is a mandatory field needed to post this form. But from where can we get  this checksum.

First of all, our website will need an API where we can generate a “checksum” which is a mandatory fields need to redirect to the Paytm website. Let us look at how to generate this checksum in the below section.

How to generate checksum

With servers build in node, we have a npm package called Paytm_App_Checksum_Kit_NodeJs which provides us two methods for generating and verifying checksum.

These are:

• genchecksum(paramarray: Object , merchant_key: string, callback):

example code:

var paytm_checksum = require('./paytm/checksum'); //use checksum.js of the above module to generate checksum

var paramarray = {};
paramarray['MID'] = 'xxxxxxxxxxxxxx';  //You merchant ID provided by paytm
paramarray['ORDER_ID'] = 'ORDER00001'; //unique OrderId for every request
paramarray['CUST_ID'] = 'CUST0001'; // unique customer identifier 
paramarray['INDUSTRY_TYPE_ID'] = 'xxxxxxxxx'; //Provided by Paytm
paramarray['CHANNEL_ID'] = 'WEB'; //Provided by Paytm
paramarray['TXN_AMOUNT'] = '1.00'; // transaction amount
paramarray['WEBSITE'] = 'xxxxxxxxxxxx'; //Provided by Paytm
paramarray['CALLBACK_URL'] = 'http://xyz/handlecallbackresponse'; //the callback url where you want paytm to be redirected after adding money to the wallet
paramarray['EMAIL'] = 'abc@gmail.com'; // customer email id
paramarray['MOBILE_NO'] = '9999999999'; // customer 10 digit mobile no.

//Generate checksum using
paytm_checksum.genchecksum(paramarray, paytm_config.MERCHANT_KEY, function (err, checksum) {
      paramarray['CHECKSUMHASH'] = checksum;
      response.writeHead(200, {'Content-type' : 'text/json','Cache-Control': 'no-cache'});
      response.write(JSON.stringify(paramarray)); 
      response.end();       
}

Above method will receive two parameters, params object with necessary fields and your merchant key. On the basis of these parameters it will generate an encrypted checksum.

Posting paytm form for redirection

Now we will use this checksum hash to post a form to the paytm website.

On our client side, we just need to add an invisible form which will post all the required parameters the paytm server:

Example:

<div style="display: none;">

  <!--Paytm Redirection Form-->
  <form name="paytmform" id="paytmform"
        action="https://pguat.paytm.com/oltp-web/processTransaction"
        method="POST">
    <input type="hidden" readonly="readonly" name="REQUEST_TYPE" value="DEFAULT"/>
    <input type="hidden" readonly="readonly" name="MID" value=""/>
    <input type="hidden" readonly="readonly" name="ORDER_ID"
           value=""/>
    <input type="hidden" readonly="readonly" name="CUST_ID" value=""/>
    <input type="hidden" readonly="readonly" name="TXN_AMOUNT" value=""/>
    <input type="hidden" readonly="readonly" name="CHANNEL_ID" value="WEB"/>
    <input type="hidden" readonly="readonly" name="CALLBACK_URL"
           value=""/>
    <input type="hidden" readonly="readonly" name="INDUSTRY_TYPE_ID"
           value=""/>
    <input type="hidden" readonly="readonly" name="WEBSITE"
           value=""/>
    <input type="hidden" readonly="readonly" name="CHECKSUMHASH"
           value=""/>
  </form>
</div>

Add all the parameters to the above form using the api used for creating checksum hash and submit this form. Rest will be handled by the paytm itself.

var form = $('#paytmform');
document.forms["paytmform"]["REQUEST_TYPE"].value = "DEFAULT";
document.forms["paytmform"]["MID"].value = response.MID;
document.forms["paytmform"]["ORDER_ID"].value = response.ORDER_ID;
document.forms["paytmform"]["CUST_ID"].value = response.CUST_ID;
document.forms["paytmform"]["TXN_AMOUNT"].value = response.TXN_AMOUNT;
document.forms["paytmform"]["CHANNEL_ID"].value = response.CHANNEL_ID;
document.forms["paytmform"]["CALLBACK_URL"].value = response.CALLBACK_URL;
document.forms["paytmform"]["INDUSTRY_TYPE_ID"].value = response.INDUSTRY_TYPE_ID;
document.forms["paytmform"]["WEBSITE"].value = response.WEBSITE;
document.forms["paytmform"]["CHECKSUMHASH"].value = response.CHECKSUM;

document.forms["paytmform"].submit();

And rest will be handled by paytm from adding money to your wallet, to making transactions.

Hope now you can easily integrate paytm wallet to your website effortlessly 🙂