<div id="result"></div>
<form method="post">
    <input type="text" name="ifsc" id="ifsc" required />
    <input type="text" name="bank_name" id="Bank" disabled placeholder="Bank Name" />
    <input type="text" name="bank_address" id="address" disabled  placeholder="Bank Address" />
    <input type="text" name="city" id="city" disabled placeholder="City Name" />
    <input type="button" name="submit"  onclick="getIFSC()" value="submit" />

</form>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

<script>
function getIFSC(){

    var ifsc = jQuery('#ifsc').val();

    if(ifsc==''){

        jQuery('#Bank').val('');
        jQuery('#address').val('');
        jQuery('#city').val('');


    }else{
        jQuery.ajax({
        url:'ifsc.php',
        data:'ifsc='+ifsc,
        type:'post',
        success:function(result){

            if(result =='no'){
                jQuery('#Bank').val('');
                jQuery('#address').val('');
                jQuery('#city').val('');

            }
            else{

            var getData=$.parseJSON(result);
            jQuery('#Bank').val(getData.branch);
            jQuery('#address').val(getData.address);
            jQuery('#city').val(getData.city);

            //console.log(getData);
            //jQuery("#result").html(result);

                    }
                }
            });
        }
}


</script>




ifsc.php

<?php

if(isset($_POST['ifsc'])){
    $ifsc = $_POST['ifsc'];
    $json = @file_get_contents('https://ifsc.razorpay.com/'.$ifsc);
    $data = json_decode($json);
    //echo '<pre>';
    //print_r($data);
    if(isset($data->BRANCH)){
        $arr['branch']=$data-> BRANCH;
        $arr['address']=$data-> ADDRESS;
        $arr['city']=$data-> CITY;

        echo json_encode($arr) ;

    //print_r($data->BRANCH);
    //echo $data->BANK ;
    //echo $data->BRANCH ;

    }

else{

        echo 'no';


    }
}



?>