diff --git a/bin/scripts/fix-data/user-merge.js b/bin/scripts/fix-data/user-merge.js
new file mode 100644
index 00000000000..78187b52109
--- /dev/null
+++ b/bin/scripts/fix-data/user-merge.js
@@ -0,0 +1,152 @@
+/**
+ *  Description: This script is used to merge users based on username.
+ *  Server: countly
+ *  Path: $(countly dir)/bin/scripts/fix-data
+ *  Command: node user-merge.js
+ */
+var pluginManager = require("../../../plugins/pluginManager.js");
+var appUsers = require("../../../api/parts/mgmt/app_users.js");
+var common = require("../../../api/utils/common.js");
+
+console.log("Merging app users");
+
+var APP_ID = "";
+var COLLECTION_NAME = "app_users" + APP_ID;
+
+var RETRY_LIMIT = 3;
+var UPDATE_COUNTER = 0;
+
+//Number of requests to be made before checking record count in app_user_merges
+var UPDATE_LIMIT = 100;
+//Number of records in app_user_merges after which script will sleep
+var RECORD_COUNT_LIMIT = 10;
+//Cooldown period if record count exceeds limit
+var RECORD_OVERLOAD_SLEEP = 2000;
+//Cooldown period between requests
+var COOLDOWN_PERIOD = 1000;
+
+const sleep = m => new Promise((r) => {
+    //console.log("Cooling period for " + m + " seconds!");
+    setTimeout(r, m);
+});
+
+pluginManager.dbConnection("countly").then(async(countlyDb) => {
+    try {
+
+        common.db = countlyDb;
+
+        await cursor();
+
+        console.log("Total updates on the server - ", UPDATE_COUNTER);
+        console.log("Script ran successfully!");
+        common.db.close();
+        process.exit(1);
+    }
+    catch (e) {
+        console.log("Error while running script ", e);
+        common.db.close();
+        process.exit(1);
+    }
+
+    async function cursor() {
+
+        const duplicates = await common.db.collection(COLLECTION_NAME).aggregate([
+            {
+                $group: {
+                    _id: "$username",
+                    count: { $sum: 1 }
+                }
+            },
+            {
+                $match: {
+                    count: { $gt: 1 },
+                    _id: { $ne: null }
+                }
+            }
+        ]).toArray();
+
+        console.log("Found", duplicates.length, "duplicate username groups.");
+
+        for (var i = 0; i < duplicates.length; i++) {
+
+            var mainUser = null;
+            var mergedUsersUIDs = [];
+
+            var query = {
+                username: duplicates[i]._id
+            };
+
+            var projections = {};
+
+            var sort = { ls: -1 };
+
+            var cursor = common.db.collection(COLLECTION_NAME).find(query).project(projections).sort(sort);
+
+            while (await cursor.hasNext()) {
+                var doc = await cursor.next();
+
+                if (doc.uid && doc.uid !== "") {
+                    if (!mainUser) {
+                        mainUser = doc;
+                    }
+                    else {
+                        await mergeUsers(mainUser, doc);
+                        mergedUsersUIDs.push(doc.uid);
+                    }
+                }
+            }
+
+            if (mergedUsersUIDs.length > 0) {
+                console.log("Total", mergedUsersUIDs.length, "users merged into user", mainUser.uid, ": (", mergedUsersUIDs.join(", "), ")");
+            }
+        }
+    }
+
+    async function mergeUsers(mainUser, user) {
+        var retryCounter = 1;
+        var success = false;
+
+        while (!success && retryCounter < RETRY_LIMIT) {
+            await new Promise(function(resolve) {
+                var newUser = JSON.parse(JSON.stringify(mainUser));
+
+                appUsers.merge(APP_ID, newUser, newUser._id, user._id, newUser.did, user.did, function(err) {
+                    if (err) {
+                        console.log("Error while merging - ", err);
+                        retryCounter += 1;
+                    }
+                    else {
+                        success = true;
+                    }
+
+                    resolve();
+                });
+            });
+            await sleep(COOLDOWN_PERIOD);
+        }
+
+        if (success) {
+            if (retryCounter > 1) {
+                console.log("User ", user.uid, " merged successfully after ", retryCounter, " retries.");
+            }
+            UPDATE_COUNTER += 1;
+            if (UPDATE_COUNTER % UPDATE_LIMIT === 0) {
+                await checkRecordCount();
+            }
+        }
+        else {
+            console.log("Retry limit exceeded for users ", mainUser.uid, " and ", user.uid);
+        }
+    }
+
+    async function checkRecordCount() {
+        var recordCount = await common.db.collection("app_user_merges").countDocuments();
+        console.log("Record count in app_user_merges: ", recordCount);
+
+        while (recordCount > RECORD_COUNT_LIMIT) {
+            console.log("Record count exceeds limit. Sleeping for " + RECORD_OVERLOAD_SLEEP / 1000 + "seconds.");
+            await sleep(RECORD_OVERLOAD_SLEEP);
+            recordCount = await common.db.collection("app_user_merges").countDocuments();
+        }
+    }
+});
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