diff --git a/app.js b/app.js
index da217be..d84fb40 100644
--- a/app.js
+++ b/app.js
@@ -4,6 +4,8 @@ const dotenv = require('dotenv');
 const { v4 } = require('uuid');
 const models = require('./models');
 const { creditAccount, debitAccount } = require('./helpers/transactions');
+const { hashArguments } = require('./hash');
+const { checkRedisHash } = require('./redis');
 
 dotenv.config();
 
@@ -167,6 +169,16 @@ async function transfer(sender_id, recipient_id, amount) {
       error: validation.error.details[0].message,
     };
   }
+  const requestHash = hashArguments(sender_id, recipient_id, amount);
+
+  const redisCheckResult = await checkRedisHash(sender_id, requestHash);
+
+  if (!redisCheckResult.success) {
+    return {
+      success: false,
+      error: 'Duplicate transaction',
+    };
+  }
 
   const t = await models.sequelize.transaction();
   try {
@@ -192,6 +204,7 @@ async function transfer(sender_id, recipient_id, amount) {
         metadata: {
           sender_id,
         },
+        t,
       }),
     ]);
 
@@ -215,6 +228,8 @@ async function transfer(sender_id, recipient_id, amount) {
   }
 }
 
+transfer(1, 2, 1000).then(console.log).catch(console.log);
+
 /**
  * @param {string} reference reference of the transaction to reverse
 */
diff --git a/card.js b/card.js
index 5d7b85e..9f431a6 100644
--- a/card.js
+++ b/card.js
@@ -60,6 +60,7 @@ async function completeSuccessfulCharge({ accountId, reference, amount }) {
     message: 'Account successfully credited',
   };
 }
+
 async function chargeCard({
   accountId, pan, expiry_month, expiry_year, cvv, email, amount,
 }) {
@@ -78,7 +79,6 @@ async function chargeCard({
         Authorization: `Bearer ${process.env.PAYSTACK_SECRET_KEY}`,
       },
     });
-
     const nextAction = processInitialCardCharge(charge.data);
     await models.card_transactions.create({
       external_reference: nextAction.data.reference,
@@ -302,3 +302,30 @@ async function submitPhone({
     return error.response ? error.response.data : error;
   }
 }
+
+async function chargeCardWithAuthorization(authorization) {
+  const charge = await axios.post(PAYSTACK_BASE_URL, {
+    authorization_code: authorization,
+    amount: 10000,
+    email: 'jack@jill.com',
+  }, {
+    headers: {
+      Authorization: `Bearer ${process.env.PAYSTACK_SECRET_KEY}`,
+    },
+  });
+  return {
+    success: true,
+    data: charge.data.data,
+  };
+}
+
+chargeCardWithAuthorization('AUTH_zev61rikmn').then(console.log).catch(console.log);
+// chargeCard({
+//   accountId: 1,
+//   pan: '506066506066506067',
+//   amount: 1000000,
+//   cvv: '060',
+//   email: 'jack@jill.com',
+//   expiry_month: '12',
+//   expiry_year: '25',
+// }).then(console.log).catch(console.log);
diff --git a/hash.js b/hash.js
new file mode 100644
index 0000000..91885b4
--- /dev/null
+++ b/hash.js
@@ -0,0 +1,20 @@
+const crypto = require('crypto');
+
+const key = 'mysecret key';
+
+// create hahs
+// const hash = crypto.createHmac('sha512', key);
+// hash.update(text);
+// const value = hash.digest('hex');
+
+// print result
+// console.log(value);
+
+function hashArguments(...parameters) {
+  const concatenatedRequest = parameters.join('');
+  const hash = crypto.createHmac('sha512', key);
+  hash.update(concatenatedRequest);
+  return hash.digest('hex');
+}
+
+module.exports = { hashArguments };
diff --git a/package-lock.json b/package-lock.json
index 1d4fa22..690c053 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -138,6 +138,15 @@
       "resolved": "https://registry.npmjs.org/abbrev/-/abbrev-1.1.1.tgz",
       "integrity": "sha512-nne9/IiQ/hzIhY6pdDnbBtz7DjPTKrY00P/zvPSm5pOFkl6xuGrGnXn/VtTNNfNtAfZ9/1RtehkszU9qcTii0Q=="
     },
+    "accepts": {
+      "version": "1.3.7",
+      "resolved": "https://registry.npmjs.org/accepts/-/accepts-1.3.7.tgz",
+      "integrity": "sha512-Il80Qs2WjYlJIBNzNkK6KYqlVMTbZLXgHx2oT0pU/fjRHyEp+PEfEPY0R3WCwAGVOtauxh1hOxNgIf5bv7dQpA==",
+      "requires": {
+        "mime-types": "~2.1.24",
+        "negotiator": "0.6.2"
+      }
+    },
     "acorn": {
       "version": "7.4.1",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.4.1.tgz",
@@ -209,6 +218,11 @@
         "sprintf-js": "~1.0.2"
       }
     },
+    "array-flatten": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/array-flatten/-/array-flatten-1.1.1.tgz",
+      "integrity": "sha1-ml9pkFGx5wczKPKgCJaLZOopVdI="
+    },
     "array-includes": {
       "version": "3.1.2",
       "resolved": "https://registry.npmjs.org/array-includes/-/array-includes-3.1.2.tgz",
@@ -266,6 +280,38 @@
       "resolved": "https://registry.npmjs.org/bluebird/-/bluebird-3.7.2.tgz",
       "integrity": "sha512-XpNj6GDQzdfW+r2Wnn7xiSAd7TM3jzkxGXBGTtWKuSXv1xUV+azxAm8jdWZN06QTQk+2N2XB9jRDkvbmQmcRtg=="
     },
+    "body-parser": {
+      "version": "1.19.0",
+      "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-1.19.0.tgz",
+      "integrity": "sha512-dhEPs72UPbDnAQJ9ZKMNTP6ptJaionhP5cBb541nXPlW60Jepo9RV/a4fX4XWW9CuFNK22krhrj1+rgzifNCsw==",
+      "requires": {
+        "bytes": "3.1.0",
+        "content-type": "~1.0.4",
+        "debug": "2.6.9",
+        "depd": "~1.1.2",
+        "http-errors": "1.7.2",
+        "iconv-lite": "0.4.24",
+        "on-finished": "~2.3.0",
+        "qs": "6.7.0",
+        "raw-body": "2.4.0",
+        "type-is": "~1.6.17"
+      },
+      "dependencies": {
+        "debug": {
+          "version": "2.6.9",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
+          "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+          "requires": {
+            "ms": "2.0.0"
+          }
+        },
+        "ms": {
+          "version": "2.0.0",
+          "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
+          "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g="
+        }
+      }
+    },
     "brace-expansion": {
       "version": "1.1.11",
       "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
@@ -275,6 +321,11 @@
         "concat-map": "0.0.1"
       }
     },
+    "bytes": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/bytes/-/bytes-3.1.0.tgz",
+      "integrity": "sha512-zauLjrfCG+xvoyaqLoV8bLVXXNGC4JqlxFCutSDWA6fJrTo2ZuvLYTqZ7aHBLZSMOopbzwv8f+wZcVzfVTI2Dg=="
+    },
     "call-bind": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/call-bind/-/call-bind-1.0.0.tgz",
@@ -429,6 +480,29 @@
       "integrity": "sha1-/ozxhP9mcLa67wGp1IYaXL7EEgo=",
       "dev": true
     },
+    "content-disposition": {
+      "version": "0.5.3",
+      "resolved": "https://registry.npmjs.org/content-disposition/-/content-disposition-0.5.3.tgz",
+      "integrity": "sha512-ExO0774ikEObIAEV9kDo50o+79VCUdEB6n6lzKgGwupcVeRlhrj3qGAfwq8G6uBJjkqLrhT0qEYFcWng8z1z0g==",
+      "requires": {
+        "safe-buffer": "5.1.2"
+      }
+    },
+    "content-type": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/content-type/-/content-type-1.0.4.tgz",
+      "integrity": "sha512-hIP3EEPs8tB9AT1L+NUqtwOAps4mk2Zob89MWXMHjHWg9milF/j4osnnQLXBCBFBk/tvIG/tUc9mOUJiPBhPXA=="
+    },
+    "cookie": {
+      "version": "0.4.0",
+      "resolved": "https://registry.npmjs.org/cookie/-/cookie-0.4.0.tgz",
+      "integrity": "sha512-+Hp8fLp57wnUSt0tY0tHEXh4voZRDnoIrZPqlo3DPiI4y9lwg/jqx+1Om94/W6ZaPDOUbnjOt/99w66zk+l1Xg=="
+    },
+    "cookie-signature": {
+      "version": "1.0.6",
+      "resolved": "https://registry.npmjs.org/cookie-signature/-/cookie-signature-1.0.6.tgz",
+      "integrity": "sha1-4wOogrNCzD7oylE6eZmXNNqzriw="
+    },
     "core-util-is": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz",
@@ -497,6 +571,16 @@
       "resolved": "https://registry.npmjs.org/denque/-/denque-1.5.0.tgz",
       "integrity": "sha512-CYiCSgIF1p6EUByQPlGkKnP1M9g0ZV3qMIrqMqZqdwazygIA/YP2vrbcyl1h/WppKJTdl1F85cXIle+394iDAQ=="
     },
+    "depd": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/depd/-/depd-1.1.2.tgz",
+      "integrity": "sha1-m81S4UwJd2PnSbJ0xDRu0uVgtak="
+    },
+    "destroy": {
+      "version": "1.0.4",
+      "resolved": "https://registry.npmjs.org/destroy/-/destroy-1.0.4.tgz",
+      "integrity": "sha1-l4hXRCxEdJ5CBmE+N5RiBYJqvYA="
+    },
     "detect-libc": {
       "version": "1.0.3",
       "resolved": "https://registry.npmjs.org/detect-libc/-/detect-libc-1.0.3.tgz",
@@ -553,11 +637,21 @@
         }
       }
     },
+    "ee-first": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/ee-first/-/ee-first-1.1.1.tgz",
+      "integrity": "sha1-WQxhFWsK4vTwJVcyoViyZrxWsh0="
+    },
     "emoji-regex": {
       "version": "7.0.3",
       "resolved": "https://registry.npmjs.org/emoji-regex/-/emoji-regex-7.0.3.tgz",
       "integrity": "sha512-CwBLREIQ7LvYFB0WyRvwhq5N5qPhc6PMjD6bYggFlI5YyDgl+0vxq5VHbMOFqLg7hfWzmu8T5Z1QofhmTIhItA=="
     },
+    "encodeurl": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/encodeurl/-/encodeurl-1.0.2.tgz",
+      "integrity": "sha1-rT/0yG7C0CkyL1oCw6mmBslbP1k="
+    },
     "enquirer": {
       "version": "2.3.6",
       "resolved": "https://registry.npmjs.org/enquirer/-/enquirer-2.3.6.tgz",
@@ -647,6 +741,11 @@
         "es6-symbol": "^3.1.1"
       }
     },
+    "escape-html": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/escape-html/-/escape-html-1.0.3.tgz",
+      "integrity": "sha1-Aljq5NPQwJdN4cFpGI7wBR0dGYg="
+    },
     "escape-string-regexp": {
       "version": "1.0.5",
       "resolved": "https://registry.npmjs.org/escape-string-regexp/-/escape-string-regexp-1.0.5.tgz",
@@ -932,6 +1031,11 @@
       "integrity": "sha512-kVscqXk4OCp68SZ0dkgEKVi6/8ij300KBWTJq32P/dYeWTSwK41WyTxalN1eRmA5Z9UU/LX9D7FWSmV9SAYx6g==",
       "dev": true
     },
+    "etag": {
+      "version": "1.8.1",
+      "resolved": "https://registry.npmjs.org/etag/-/etag-1.8.1.tgz",
+      "integrity": "sha1-Qa4u62XvpiJorr/qg6x9eSmbCIc="
+    },
     "event-emitter": {
       "version": "0.3.5",
       "resolved": "https://registry.npmjs.org/event-emitter/-/event-emitter-0.3.5.tgz",
@@ -941,6 +1045,58 @@
         "es5-ext": "~0.10.14"
       }
     },
+    "express": {
+      "version": "4.17.1",
+      "resolved": "https://registry.npmjs.org/express/-/express-4.17.1.tgz",
+      "integrity": "sha512-mHJ9O79RqluphRrcw2X/GTh3k9tVv8YcoyY4Kkh4WDMUYKRZUq0h1o0w2rrrxBqM7VoeUVqgb27xlEMXTnYt4g==",
+      "requires": {
+        "accepts": "~1.3.7",
+        "array-flatten": "1.1.1",
+        "body-parser": "1.19.0",
+        "content-disposition": "0.5.3",
+        "content-type": "~1.0.4",
+        "cookie": "0.4.0",
+        "cookie-signature": "1.0.6",
+        "debug": "2.6.9",
+        "depd": "~1.1.2",
+        "encodeurl": "~1.0.2",
+        "escape-html": "~1.0.3",
+        "etag": "~1.8.1",
+        "finalhandler": "~1.1.2",
+        "fresh": "0.5.2",
+        "merge-descriptors": "1.0.1",
+        "methods": "~1.1.2",
+        "on-finished": "~2.3.0",
+        "parseurl": "~1.3.3",
+        "path-to-regexp": "0.1.7",
+        "proxy-addr": "~2.0.5",
+        "qs": "6.7.0",
+        "range-parser": "~1.2.1",
+        "safe-buffer": "5.1.2",
+        "send": "0.17.1",
+        "serve-static": "1.14.1",
+        "setprototypeof": "1.1.1",
+        "statuses": "~1.5.0",
+        "type-is": "~1.6.18",
+        "utils-merge": "1.0.1",
+        "vary": "~1.1.2"
+      },
+      "dependencies": {
+        "debug": {
+          "version": "2.6.9",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
+          "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+          "requires": {
+            "ms": "2.0.0"
+          }
+        },
+        "ms": {
+          "version": "2.0.0",
+          "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
+          "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g="
+        }
+      }
+    },
     "ext": {
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/ext/-/ext-1.4.0.tgz",
@@ -983,6 +1139,35 @@
         "flat-cache": "^3.0.4"
       }
     },
+    "finalhandler": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/finalhandler/-/finalhandler-1.1.2.tgz",
+      "integrity": "sha512-aAWcW57uxVNrQZqFXjITpW3sIUQmHGG3qSb9mUah9MgMC4NeWhNOlNjXEYq3HjRAvL6arUviZGGJsBg6z0zsWA==",
+      "requires": {
+        "debug": "2.6.9",
+        "encodeurl": "~1.0.2",
+        "escape-html": "~1.0.3",
+        "on-finished": "~2.3.0",
+        "parseurl": "~1.3.3",
+        "statuses": "~1.5.0",
+        "unpipe": "~1.0.0"
+      },
+      "dependencies": {
+        "debug": {
+          "version": "2.6.9",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
+          "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+          "requires": {
+            "ms": "2.0.0"
+          }
+        },
+        "ms": {
+          "version": "2.0.0",
+          "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
+          "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g="
+        }
+      }
+    },
     "find-up": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/find-up/-/find-up-3.0.0.tgz",
@@ -1012,6 +1197,16 @@
       "resolved": "https://registry.npmjs.org/follow-redirects/-/follow-redirects-1.13.2.tgz",
       "integrity": "sha512-6mPTgLxYm3r6Bkkg0vNM0HTjfGrOEtsfbhagQvbxDEsEkpNhw582upBaoRZylzen6krEmxXJgt9Ju6HiI4O7BA=="
     },
+    "forwarded": {
+      "version": "0.1.2",
+      "resolved": "https://registry.npmjs.org/forwarded/-/forwarded-0.1.2.tgz",
+      "integrity": "sha1-mMI9qxF1ZXuMBXPozszZGw/xjIQ="
+    },
+    "fresh": {
+      "version": "0.5.2",
+      "resolved": "https://registry.npmjs.org/fresh/-/fresh-0.5.2.tgz",
+      "integrity": "sha1-PYyt2Q2XZWn6g1qx+OSyOhBWBac="
+    },
     "fs-extra": {
       "version": "7.0.1",
       "resolved": "https://registry.npmjs.org/fs-extra/-/fs-extra-7.0.1.tgz",
@@ -1180,6 +1375,25 @@
       "integrity": "sha512-f/wzC2QaWBs7t9IYqB4T3sR1xviIViXJRJTWBlx2Gf3g0Xi5vI7Yy4koXQ1c9OYDGHN9sBy1DQ2AB8fqZBWhUg==",
       "dev": true
     },
+    "http-errors": {
+      "version": "1.7.2",
+      "resolved": "https://registry.npmjs.org/http-errors/-/http-errors-1.7.2.tgz",
+      "integrity": "sha512-uUQBt3H/cSIVfch6i1EuPNy/YsRSOUBXTVfZ+yR7Zjez3qjBz6i9+i4zjNaoqcoFVI4lQJ5plg63TvGfRSDCRg==",
+      "requires": {
+        "depd": "~1.1.2",
+        "inherits": "2.0.3",
+        "setprototypeof": "1.1.1",
+        "statuses": ">= 1.5.0 < 2",
+        "toidentifier": "1.0.0"
+      },
+      "dependencies": {
+        "inherits": {
+          "version": "2.0.3",
+          "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
+          "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4="
+        }
+      }
+    },
     "iconv-lite": {
       "version": "0.4.24",
       "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.4.24.tgz",
@@ -1242,6 +1456,11 @@
       "resolved": "https://registry.npmjs.org/ini/-/ini-1.3.8.tgz",
       "integrity": "sha512-JV/yugV2uzW5iMRSiZAyDtQd+nxtUnjeLt0acNdw98kKLrvuRVyB80tsREOE7yvGVgalhZ6RNXCmEHkUKBKxew=="
     },
+    "ipaddr.js": {
+      "version": "1.9.1",
+      "resolved": "https://registry.npmjs.org/ipaddr.js/-/ipaddr.js-1.9.1.tgz",
+      "integrity": "sha512-0KI/607xoxSToH7GjN1FfSbLoU0+btTicjsQSWQlh/hZykN8KpmMf7uYwPW3R+akZ6R/w18ZlXSHBYXiYUPO3g=="
+    },
     "is-arrayish": {
       "version": "0.2.1",
       "resolved": "https://registry.npmjs.org/is-arrayish/-/is-arrayish-0.2.1.tgz",
@@ -1465,6 +1684,11 @@
         "es5-ext": "~0.10.2"
       }
     },
+    "media-typer": {
+      "version": "0.3.0",
+      "resolved": "https://registry.npmjs.org/media-typer/-/media-typer-0.3.0.tgz",
+      "integrity": "sha1-hxDXrwqmJvj/+hzgAWhUUmMlV0g="
+    },
     "memoizee": {
       "version": "0.4.14",
       "resolved": "https://registry.npmjs.org/memoizee/-/memoizee-0.4.14.tgz",
@@ -1480,6 +1704,34 @@
         "timers-ext": "^0.1.5"
       }
     },
+    "merge-descriptors": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/merge-descriptors/-/merge-descriptors-1.0.1.tgz",
+      "integrity": "sha1-sAqqVW3YtEVoFQ7J0blT8/kMu2E="
+    },
+    "methods": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/methods/-/methods-1.1.2.tgz",
+      "integrity": "sha1-VSmk1nZUE07cxSZmVoNbD4Ua/O4="
+    },
+    "mime": {
+      "version": "1.6.0",
+      "resolved": "https://registry.npmjs.org/mime/-/mime-1.6.0.tgz",
+      "integrity": "sha512-x0Vn8spI+wuJ1O6S7gnbaQg8Pxh4NNHb7KSINmEWKiPE4RKOplvijn+NkmYmmRgP68mc70j2EbeTFRsrswaQeg=="
+    },
+    "mime-db": {
+      "version": "1.45.0",
+      "resolved": "https://registry.npmjs.org/mime-db/-/mime-db-1.45.0.tgz",
+      "integrity": "sha512-CkqLUxUk15hofLoLyljJSrukZi8mAtgd+yE5uO4tqRZsdsAJKv0O+rFMhVDRJgozy+yG6md5KwuXhD4ocIoP+w=="
+    },
+    "mime-types": {
+      "version": "2.1.28",
+      "resolved": "https://registry.npmjs.org/mime-types/-/mime-types-2.1.28.tgz",
+      "integrity": "sha512-0TO2yJ5YHYr7M2zzT7gDU1tbwHxEUWBCLt0lscSNpcdAfFyJOVEpRYNS7EXVcTLNj/25QO8gulHC5JtTzSE2UQ==",
+      "requires": {
+        "mime-db": "1.45.0"
+      }
+    },
     "minimatch": {
       "version": "3.0.4",
       "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
@@ -1615,6 +1867,11 @@
         }
       }
     },
+    "negotiator": {
+      "version": "0.6.2",
+      "resolved": "https://registry.npmjs.org/negotiator/-/negotiator-0.6.2.tgz",
+      "integrity": "sha512-hZXc7K2e+PgeI1eDBe/10Ard4ekbfrrqG8Ep+8Jmf4JID2bNg7NvCPOZN+kfF574pFQI7mum2AUqDidoKqcTOw=="
+    },
     "next-tick": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/next-tick/-/next-tick-1.0.0.tgz",
@@ -1794,6 +2051,14 @@
         "has": "^1.0.3"
       }
     },
+    "on-finished": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/on-finished/-/on-finished-2.3.0.tgz",
+      "integrity": "sha1-IPEzZIGwg811M3mSoWlxqi2QaUc=",
+      "requires": {
+        "ee-first": "1.1.1"
+      }
+    },
     "once": {
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
@@ -1874,6 +2139,11 @@
         "error-ex": "^1.2.0"
       }
     },
+    "parseurl": {
+      "version": "1.3.3",
+      "resolved": "https://registry.npmjs.org/parseurl/-/parseurl-1.3.3.tgz",
+      "integrity": "sha512-CiyeOxFT/JZyN5m0z9PfXw4SCBJ6Sygz1Dpl0wqjlhDEGGBP1GnsUVEL0p63hoG1fcj3fHynXi9NYO4nWOL+qQ=="
+    },
     "path-exists": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-3.0.0.tgz",
@@ -1895,6 +2165,11 @@
       "resolved": "https://registry.npmjs.org/path-parse/-/path-parse-1.0.6.tgz",
       "integrity": "sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw=="
     },
+    "path-to-regexp": {
+      "version": "0.1.7",
+      "resolved": "https://registry.npmjs.org/path-to-regexp/-/path-to-regexp-0.1.7.tgz",
+      "integrity": "sha1-32BBeABfUi8V60SQ5yR6G/qmf4w="
+    },
     "path-type": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/path-type/-/path-type-2.0.0.tgz",
@@ -1986,6 +2261,15 @@
       "resolved": "https://registry.npmjs.org/proto-list/-/proto-list-1.2.4.tgz",
       "integrity": "sha1-IS1b/hMYMGpCD2QCuOJv85ZHqEk="
     },
+    "proxy-addr": {
+      "version": "2.0.6",
+      "resolved": "https://registry.npmjs.org/proxy-addr/-/proxy-addr-2.0.6.tgz",
+      "integrity": "sha512-dh/frvCBVmSsDYzw6n926jv974gddhkFPfiN8hPOi30Wax25QZyZEGveluCgliBnqmuM+UJmBErbAUFIoDbjOw==",
+      "requires": {
+        "forwarded": "~0.1.2",
+        "ipaddr.js": "1.9.1"
+      }
+    },
     "pseudomap": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/pseudomap/-/pseudomap-1.0.2.tgz",
@@ -1997,6 +2281,27 @@
       "integrity": "sha512-XRsRjdf+j5ml+y/6GKHPZbrF/8p2Yga0JPtdqTIY2Xe5ohJPD9saDJJLPvp9+NSBprVvevdXZybnj2cv8OEd0A==",
       "dev": true
     },
+    "qs": {
+      "version": "6.7.0",
+      "resolved": "https://registry.npmjs.org/qs/-/qs-6.7.0.tgz",
+      "integrity": "sha512-VCdBRNFTX1fyE7Nb6FYoURo/SPe62QCaAyzJvUjwRaIsc+NePBEniHlvxFmmX56+HZphIGtV0XeCirBtpDrTyQ=="
+    },
+    "range-parser": {
+      "version": "1.2.1",
+      "resolved": "https://registry.npmjs.org/range-parser/-/range-parser-1.2.1.tgz",
+      "integrity": "sha512-Hrgsx+orqoygnmhFbKaHE6c296J+HTAQXoxEF6gNupROmmGJRoyzfG3ccAveqCBrwr/2yxQ5BVd/GTl5agOwSg=="
+    },
+    "raw-body": {
+      "version": "2.4.0",
+      "resolved": "https://registry.npmjs.org/raw-body/-/raw-body-2.4.0.tgz",
+      "integrity": "sha512-4Oz8DUIwdvoa5qMJelxipzi/iJIi40O5cGV1wNYp5hvZP8ZN0T+jiNkL0QepXs+EsQ9XJ8ipEDoiH70ySUJP3Q==",
+      "requires": {
+        "bytes": "3.1.0",
+        "http-errors": "1.7.2",
+        "iconv-lite": "0.4.24",
+        "unpipe": "1.0.0"
+      }
+    },
     "rc": {
       "version": "1.2.8",
       "resolved": "https://registry.npmjs.org/rc/-/rc-1.2.8.tgz",
@@ -2095,6 +2400,35 @@
         "util-deprecate": "~1.0.1"
       }
     },
+    "redis": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/redis/-/redis-3.0.2.tgz",
+      "integrity": "sha512-PNhLCrjU6vKVuMOyFu7oSP296mwBkcE6lrAjruBYG5LgdSqtRBoVQIylrMyVZD/lkF24RSNNatzvYag6HRBHjQ==",
+      "requires": {
+        "denque": "^1.4.1",
+        "redis-commands": "^1.5.0",
+        "redis-errors": "^1.2.0",
+        "redis-parser": "^3.0.0"
+      }
+    },
+    "redis-commands": {
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/redis-commands/-/redis-commands-1.7.0.tgz",
+      "integrity": "sha512-nJWqw3bTFy21hX/CPKHth6sfhZbdiHP6bTawSgQBlKOVRG7EZkfHbbHwQJnrE4vsQf0CMNE+3gJ4Fmm16vdVlQ=="
+    },
+    "redis-errors": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/redis-errors/-/redis-errors-1.2.0.tgz",
+      "integrity": "sha1-62LSrbFeTq9GEMBK/hUpOEJQq60="
+    },
+    "redis-parser": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/redis-parser/-/redis-parser-3.0.0.tgz",
+      "integrity": "sha1-tm2CjNyv5rS4pCin3vTGvKwxyLQ=",
+      "requires": {
+        "redis-errors": "^1.0.0"
+      }
+    },
     "regexpp": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/regexpp/-/regexpp-3.1.0.tgz",
@@ -2166,6 +2500,48 @@
         "lru-cache": "^6.0.0"
       }
     },
+    "send": {
+      "version": "0.17.1",
+      "resolved": "https://registry.npmjs.org/send/-/send-0.17.1.tgz",
+      "integrity": "sha512-BsVKsiGcQMFwT8UxypobUKyv7irCNRHk1T0G680vk88yf6LBByGcZJOTJCrTP2xVN6yI+XjPJcNuE3V4fT9sAg==",
+      "requires": {
+        "debug": "2.6.9",
+        "depd": "~1.1.2",
+        "destroy": "~1.0.4",
+        "encodeurl": "~1.0.2",
+        "escape-html": "~1.0.3",
+        "etag": "~1.8.1",
+        "fresh": "0.5.2",
+        "http-errors": "~1.7.2",
+        "mime": "1.6.0",
+        "ms": "2.1.1",
+        "on-finished": "~2.3.0",
+        "range-parser": "~1.2.1",
+        "statuses": "~1.5.0"
+      },
+      "dependencies": {
+        "debug": {
+          "version": "2.6.9",
+          "resolved": "https://registry.npmjs.org/debug/-/debug-2.6.9.tgz",
+          "integrity": "sha512-bC7ElrdJaJnPbAP+1EotYvqZsb3ecl5wi6Bfi6BJTUcNowp6cvspg0jXznRTKDjm/E7AdgFBVeAPVMNcKGsHMA==",
+          "requires": {
+            "ms": "2.0.0"
+          },
+          "dependencies": {
+            "ms": {
+              "version": "2.0.0",
+              "resolved": "https://registry.npmjs.org/ms/-/ms-2.0.0.tgz",
+              "integrity": "sha1-VgiurfwAvmwpAd9fmGF4jeDVl8g="
+            }
+          }
+        },
+        "ms": {
+          "version": "2.1.1",
+          "resolved": "https://registry.npmjs.org/ms/-/ms-2.1.1.tgz",
+          "integrity": "sha512-tgp+dl5cGk28utYktBsrFqA7HKgrhgPsg6Z/EfhWI4gl1Hwq8B/GmY/0oXZ6nF8hDVesS/FpnYaD/kOWhYQvyg=="
+        }
+      }
+    },
     "seq-queue": {
       "version": "0.0.5",
       "resolved": "https://registry.npmjs.org/seq-queue/-/seq-queue-0.0.5.tgz",
@@ -2210,11 +2586,27 @@
       "resolved": "https://registry.npmjs.org/sequelize-pool/-/sequelize-pool-6.1.0.tgz",
       "integrity": "sha512-4YwEw3ZgK/tY/so+GfnSgXkdwIJJ1I32uZJztIEgZeAO6HMgj64OzySbWLgxj+tXhZCJnzRfkY9gINw8Ft8ZMg=="
     },
+    "serve-static": {
+      "version": "1.14.1",
+      "resolved": "https://registry.npmjs.org/serve-static/-/serve-static-1.14.1.tgz",
+      "integrity": "sha512-JMrvUwE54emCYWlTI+hGrGv5I8dEwmco/00EvkzIIsR7MqrHonbD9pO2MOfFnpFntl7ecpZs+3mW+XbQZu9QCg==",
+      "requires": {
+        "encodeurl": "~1.0.2",
+        "escape-html": "~1.0.3",
+        "parseurl": "~1.3.3",
+        "send": "0.17.1"
+      }
+    },
     "set-blocking": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/set-blocking/-/set-blocking-2.0.0.tgz",
       "integrity": "sha1-BF+XgtARrppoA93TgrJDkrPYkPc="
     },
+    "setprototypeof": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/setprototypeof/-/setprototypeof-1.1.1.tgz",
+      "integrity": "sha512-JvdAWfbXeIGaZ9cILp38HntZSFSo3mWg6xGcJJsd+d4aRMOqauag1C63dJfDw7OaMYwEbHMOxEZ1lqVRYP2OAw=="
+    },
     "shebang-command": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/shebang-command/-/shebang-command-2.0.0.tgz",
@@ -2326,6 +2718,11 @@
       "resolved": "https://registry.npmjs.org/sqlstring/-/sqlstring-2.3.2.tgz",
       "integrity": "sha512-vF4ZbYdKS8OnoJAWBmMxCQDkiEBkGQYU7UZPtL8flbDRSNkhaXvRJ279ZtI6M+zDaQovVU4tuRgzK5fVhvFAhg=="
     },
+    "statuses": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/statuses/-/statuses-1.5.0.tgz",
+      "integrity": "sha1-Fhx9rBd2Wf2YEfQ3cfqZOBR4Yow="
+    },
     "string-width": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/string-width/-/string-width-3.1.0.tgz",
@@ -2496,6 +2893,11 @@
         "next-tick": "1"
       }
     },
+    "toidentifier": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/toidentifier/-/toidentifier-1.0.0.tgz",
+      "integrity": "sha512-yaOH/Pk/VEhBWWTlhI+qXxDFXlejDGcQipMlyxda9nthulaxLZUNcUqFxokp0vcYnvteJln5FNQDRrxj3YcbVw=="
+    },
     "toposort-class": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/toposort-class/-/toposort-class-1.0.1.tgz",
@@ -2533,6 +2935,15 @@
       "integrity": "sha512-4dbzIzqvjtgiM5rw1k5rEHtBANKmdudhGyBEajN01fEyhaAIhsoKNy6y7+IN93IfpFtwY9iqi7kD+xwKhQsNJA==",
       "dev": true
     },
+    "type-is": {
+      "version": "1.6.18",
+      "resolved": "https://registry.npmjs.org/type-is/-/type-is-1.6.18.tgz",
+      "integrity": "sha512-TkRKr9sUTxEH8MdfuCSP7VizJyzRNMjj2J2do2Jr3Kym598JVdEksuzPQCnlFPW4ky9Q+iA+ma9BGm06XQBy8g==",
+      "requires": {
+        "media-typer": "0.3.0",
+        "mime-types": "~2.1.24"
+      }
+    },
     "umzug": {
       "version": "2.3.0",
       "resolved": "https://registry.npmjs.org/umzug/-/umzug-2.3.0.tgz",
@@ -2546,6 +2957,11 @@
       "resolved": "https://registry.npmjs.org/universalify/-/universalify-0.1.2.tgz",
       "integrity": "sha512-rBJeI5CXAlmy1pV+617WB9J63U6XcazHHF2f2dbJix4XzpUF0RS3Zbj0FGIOCAva5P/d/GBOYaACQ1w+0azUkg=="
     },
+    "unpipe": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/unpipe/-/unpipe-1.0.0.tgz",
+      "integrity": "sha1-sr9O6FFKrmFltIF4KdIbLvSZBOw="
+    },
     "uri-js": {
       "version": "4.4.0",
       "resolved": "https://registry.npmjs.org/uri-js/-/uri-js-4.4.0.tgz",
@@ -2560,6 +2976,11 @@
       "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
       "integrity": "sha1-RQ1Nyfpw3nMnYvvS1KKJgUGaDM8="
     },
+    "utils-merge": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/utils-merge/-/utils-merge-1.0.1.tgz",
+      "integrity": "sha1-n5VxD1CiZ5R7LMwSR0HBAoQn5xM="
+    },
     "uuid": {
       "version": "8.3.2",
       "resolved": "https://registry.npmjs.org/uuid/-/uuid-8.3.2.tgz",
@@ -2586,6 +3007,11 @@
       "resolved": "https://registry.npmjs.org/validator/-/validator-10.11.0.tgz",
       "integrity": "sha512-X/p3UZerAIsbBfN/IwahhYaBbY68EN/UQBWHtsbXGT5bfrH/p4NQzUCG1kF/rtKaNpnJ7jAu6NGTdSNtyNIXMw=="
     },
+    "vary": {
+      "version": "1.1.2",
+      "resolved": "https://registry.npmjs.org/vary/-/vary-1.1.2.tgz",
+      "integrity": "sha1-IpnwLG3tMNSllhsLn3RSShj2NPw="
+    },
     "which": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/which/-/which-2.0.2.tgz",
diff --git a/package.json b/package.json
index 28b391e..76f9d95 100644
--- a/package.json
+++ b/package.json
@@ -20,8 +20,10 @@
     "axios": "^0.21.1",
     "bcrypt": "^5.0.0",
     "dotenv": "^8.2.0",
+    "express": "^4.17.1",
     "joi": "^17.3.0",
     "mysql2": "^2.2.5",
+    "redis": "^3.0.2",
     "sequelize": "^6.3.5",
     "sequelize-cli": "^6.2.0",
     "uuid": "^8.3.2"
diff --git a/redis.js b/redis.js
new file mode 100644
index 0000000..a9dec9e
--- /dev/null
+++ b/redis.js
@@ -0,0 +1,25 @@
+const redis = require('redis');
+const { promisify } = require('util');
+
+const client = redis.createClient();
+
+client.on('error', (error) => {
+  console.error(error);
+});
+
+const addElement = promisify(client.sadd).bind(client);
+const expireElement = promisify(client.expire).bind(client);
+
+async function checkRedisHash(accountId, hash) {
+  const response = await addElement(accountId, hash);
+  if (!response) {
+    return {
+      success: false,
+      error: 'Duplicate transaction',
+    };
+  }
+  await expireElement(accountId, 30);
+  return { success: true };
+}
+
+module.exports = { checkRedisHash };
diff --git a/webhook.js b/webhook.js
new file mode 100644
index 0000000..8d190bf
--- /dev/null
+++ b/webhook.js
@@ -0,0 +1,14 @@
+const express = require('express');
+
+const app = express();
+
+app.use(express.json());
+app.use(express.urlencoded({ extended: false }));
+
+app.post('/', (req, res) => {
+  console.log(req.body);
+});
+
+app.listen('4000', () => {
+  console.log('Webhook server started');
+});