Direct API Step 2

<?php

    $post = $_POST;

    $merchant_key   = 'YYYYYYYYYYYYYY';
    $merchant_salt  = 'ZZZZZZZZZZZZZZ';

    $hash = base64_encode( hash_hmac('sha256', $post['merchant_oid'].$merchant_salt.$post['status'].$post['total_amount'], $merchant_key, true) );

    if( $hash != $post['hash'] )
        die('PAYTR notification failed: bad hash');

    if( $post['status'] == 'success' ) { 

    } else { 

    }

    echo "OK";
    exit;
?>

# Python 3.6+

import base64
import hashlib
import hmac

from django.shortcuts import render, HttpResponse
from django.views.decorators.csrf import csrf_exempt

@csrf_exempt
def callback(request):

    if request.method != 'POST':
        return HttpResponse(str(''))

    post = request.POST

    merchant_key = b'YYYYYYYYYYYYYY'
    merchant_salt = 'ZZZZZZZZZZZZZZ'

    hash_str = post['merchant_oid'] + merchant_salt + post['status'] + post['total_amount']
    hash = base64.b64encode(hmac.new(merchant_key, hash_str.encode(), hashlib.sha256).digest())

    if hash != post['hash']:
        return HttpResponse(str('PAYTR notification failed: bad hash'))

    if post['status'] == 'success':  

        print(request)
    else:  

        print(request)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Web;
using System.Net.Mail;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class bildirim_url_ornek : System.Web.UI.Page {

    string merchant_key     = "YYYYYYYYYYYYYY";
    string merchant_salt    = "ZZZZZZZZZZZZZZ";

    protected void Page_Load(object sender, EventArgs e) {

        string merchant_oid = Request.Form["merchant_oid"];
        string status = Request.Form["status"];
        string total_amount = Request.Form["total_amount"];
        string hash = Request.Form["hash"];

        string Birlestir = string.Concat(merchant_oid, merchant_salt, status, total_amount);
        HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(merchant_key));
        byte[] b = hmac.ComputeHash(Encoding.UTF8.GetBytes(Birlestir));
        string token = Convert.ToBase64String(b);

        if (hash.ToString() != token) {
            Response.Write("PAYTR notification failed: bad hash");
            return;
            }

        if (status == "success") {   
            Response.Write("OK");

            } else { 
            Response.Write("OK");

            }          
    }
}

var express = require('express');
var ejsLayouts = require('express-ejs-layouts');
var microtime = require('microtime');
var crypto = require('crypto');
var nodeBase64 = require('nodejs-base64-converter');
var app = express();
var path = require('path');

app.set('views', path.join(__dirname, '/app_server/views'));

app.set('view engine', 'ejs');
app.use(ejsLayouts);
app.use(express.json());
app.use(express.urlencoded({ extended: true }));

// API - Information Integration  - You can get them from the information page after logging into the PayTR Merchant Panel.

var merchant_id = 'merchant_number';
var merchant_key = 'XXXXXXXXXXX';
var merchant_salt = 'YYYYYYYYYYY';
var basket = JSON.stringify([
    ['Sample Product 1', '50.00', 1], // 1st Product (Product Name - Unit Price - Piece)
    ['Sample Product 2', '33.25', 2], // 2nd Product (Product Name - Unit Price - Piece)
    ['Sample Product 3', '45.42', 1] // 3rd Product (Product Name - Unit Price - Piece)
]);
var user_basket = basket;
var merchant_oid = "IN" + microtime.now(); 
var user_ip = '';
var email = 'testnon3d@paytr.com'; 
var payment_amount = '100.99';
var currency = 'TL';
var test_mode = '0';
var user_name = 'PayTR Test';
var user_address = 'test test test'; 
var user_phone = '05555555555';
// The page where your customer will be directed after successful payment.
var merchant_ok_url = 'http://www.siteniz.com/odeme_basarili.php';
// The page where your customer will be directed after fail payment.
var merchant_fail_url = 'http://www.siteniz.com/odeme_hata.php';
var debug_on = 1;
var client_lang = 'en'; //tr for Turkish or en for English (tr is assumed if not sent)
var payment_type = 'card'; 
var non_3d = '0'; // For Non3D transactions send this value as 1
var card_type = '';  
var installment_count = '0'; 

//If you need to test failed Non3D transaction send 1 (non_3d and test_mode values must be both 1)
var non3d_test_failed = '0';

app.get("/", function (req, res) {

    var hashSTR = `${merchant_id}${user_ip}${merchant_oid}${email}${payment_amount}${payment_type}${installment_count}${currency}${test_mode}${non_3d}`;
    console.log('HASH STR' + hashSTR);
    var paytr_token = hashSTR + merchant_salt;
    console.log('PAYTR TOKEN' + paytr_token);
    var token = crypto.createHmac('sha256', merchant_key).update(paytr_token).digest('base64');

    console.log('TOKEN' + token);
    context = {
        merchant_id,
        user_ip,
        merchant_oid,
        email,
        payment_type,
        payment_amount,
        currency,
        test_mode,
        non_3d,
        merchant_ok_url,
        merchant_fail_url,
        user_name,
        user_address,
        user_phone,
        user_basket,
        debug_on,
        client_lang,
        token,
        non3d_test_failed,
        installment_count,
        card_type,
    };

    res.render('index');

});

app.post("/callback", function (req, res) {

    var callback = req.body;

    paytr_token = callback.merchant_oid + merchant_salt + callback.status + callback.total_amount;
    var token = crypto.createHmac('sha256', merchant_key).update(paytr_token).digest('base64');

    if (token != callback.hash) {
        throw new Error("PAYTR notification failed: bad hash");
    }

    if (callback.status == 'success') {
        // success
    } else {
        /// failed
    }

    res.send('OK');  // Notify the PayTR system that the notification has been received.  

});

var port = 3200;
app.listen(port, function () {
    console.log("Server is running. Port:" + port);
});