Validating UPI IDs Using a Secure API

public class UPIResponse
{
    public string vpa { get; set; }
    public string customer_name { get; set; }
    public bool success { get; set; }
}
public class UPIErrorResponse
{
    public UPIError error { get; set; }
}
public class UPIError
{
    public string code { get; set; }
    public string description { get; set; }
    public string source { get; set; }
    public string step { get; set; }
    public string reason { get; set; }
}

JavaScript Frontend (AJAX Call)

<div class="bid-content-common bid-content-3">
    <label class="upiid-lble">UPI ID</label>
    <input id="txtupiid" runat="server" type="text" placeholder="Enter the UPI ID"
           onchange="UPIIDtxtboxchanges()" onblur="handleBlur()" />
    <span id="upidtxt"></span>
    <input id="upidvalidation" type="hidden" />
    <button id="applybtn">Apply</button>
</div>

<script>
    function UPIIDtxtboxchanges() {
        var applybtn = document.getElementById("applybtn");
        var upitxt = document.getElementById("upidvalidation");
        var txtbutton = document.getElementById("txtupiid");
        var verifytxt = document.getElementById("upidtxt");

        upitxt.value = 'Verify';
        upitxt.style.backgroundColor = "#F0F0F0";
        upitxt.style.border = "2px solid #979F6E";
        upitxt.style.color = "black";
        verifytxt.innerText = "";
        applybtn.style.pointerEvents = "auto";
    }

    function handleBlur() {
        // Assuming upivalidationmethod takes a callback function
        upivalidationmethod(function (isValid) {
            if (isValid) {
                return true;
            } else {
                return false;
            }
        });
    }

    function upivalidationmethod(callback) {
        var upiId = document.getElementById("upiInput").value;

        $.ajax({
            type: "POST",
            url: "/your-page.aspx/ValidateUPI",
            contentType: "application/json; charset=utf-8",
            data: JSON.stringify({ upi: upiId }),
            success: function (res) {
                var status = res.d.split('-');
                if (status[0] === "success") {
                    $("#message").text("Valid UPI: " + status[1]).css("color", "green");
                    callback(true);
                } else {
                    $("#message").text("Invalid UPI").css("color", "red");
                    callback(false);
                }
            },
            error: function () {
                $("#message").text("Error validating UPI").css("color", "red");
                callback(false);
            }
        });
    }
</script>

Best Practices

• Always encrypt sensitive credentials used in API headers.
• Validate and sanitize inputs to avoid injection or malformed requests.
• Log and monitor UPI validation failures for system analysis.

Conclusion

Integrating a UPI ID validation step into your application ensures smoother payments, fewer failed transactions, and a better user experience. Using an API for this process helps streamline validation with real-time customer name checks and error handling. Replace the dummy API URL and credentials with your actual provider’s details securely in production.