diff --git a/src/handlers/noproxyHandler.js b/src/handlers/noproxyHandler.js
index 205b45f..1f5f126 100644
--- a/src/handlers/noproxyHandler.js
+++ b/src/handlers/noproxyHandler.js
@@ -29,8 +29,8 @@ function noproxyHandler(req, socket, head) {
   // SVR.JS configuration object (modified)
   const config = deepClone(process.serverConfig);
 
-  var reqip = socket.remoteAddress;
-  var reqport = socket.remotePort;
+  const reqip = socket.remoteAddress;
+  const reqport = socket.remotePort;
   process.reqcounter++;
   logFacilities.locmessage(
     `Somebody connected to ${
diff --git a/src/handlers/proxyHandler.js b/src/handlers/proxyHandler.js
index 4bf8f9d..f3e60bf 100644
--- a/src/handlers/proxyHandler.js
+++ b/src/handlers/proxyHandler.js
@@ -36,8 +36,8 @@ function proxyHandler(req, socket, head) {
     return generateServerString(config.exposeServerVersion);
   };
 
-  var reqip = socket.remoteAddress;
-  var reqport = socket.remotePort;
+  const reqip = socket.remoteAddress;
+  const reqport = socket.remotePort;
   process.reqcounter++;
   logFacilities.locmessage(
     `Somebody connected to ${
diff --git a/src/index.js b/src/index.js
index 41b8452..7d0e436 100644
--- a/src/index.js
+++ b/src/index.js
@@ -422,7 +422,7 @@ try {
 } catch (err) {
   ifaceEx = err;
 }
-var ips = [];
+let ips = [];
 const brdIPs = ["255.255.255.255", "127.255.255.255", "0.255.255.255"];
 const netIPs = ["127.0.0.0"];
 
@@ -461,7 +461,7 @@ if (ips.length == 0) {
 }
 
 // Server IP address
-var host = ips[ips.length - 1];
+let host = ips[ips.length - 1];
 if (!host) host = "[offline]";
 
 // Public IP address-related
@@ -1132,7 +1132,7 @@ if (process.serverConfig.secure) {
         key: sniCredentialsSingle.key,
       });
       try {
-        var snMatches = sniCredentialsSingle.name.match(
+        let snMatches = sniCredentialsSingle.name.match(
           /^([^:[]*|\[[^]]*\]?)((?::.*)?)$/,
         );
         if (!snMatches[1][0].match(/^\.+$/))
@@ -1414,7 +1414,7 @@ function SVRJSFork() {
       "Starting next thread, because previous one hung up/crashed...",
     );
   // Fork new worker
-  var newWorker = {};
+  let newWorker = {};
   try {
     if (
       !threadLimitWarned &&
@@ -1518,7 +1518,7 @@ function getWorkerCountToFork() {
 }
 
 function forkWorkers(workersToFork, callback) {
-  for (var i = 0; i < workersToFork; i++) {
+  for (let i = 0; i < workersToFork; i++) {
     if (i == 0) {
       SVRJSFork();
     } else {
@@ -1582,9 +1582,9 @@ function msgListener(message) {
 
 // Save configuration file
 function saveConfig() {
-  for (var i = 0; i < 3; i++) {
+  for (let i = 0; i < 3; i++) {
     try {
-      var configJSONobj = {};
+      let configJSONobj = {};
       if (fs.existsSync(process.dirname + "/config.json"))
         configJSONobj = JSON.parse(
           fs.readFileSync(process.dirname + "/config.json").toString(),
@@ -1674,12 +1674,11 @@ function saveConfig() {
       if (configJSONobj.optOutOfStatisticsServer === undefined)
         configJSONobj.optOutOfStatisticsServer = false;
 
-      var configString = JSON.stringify(configJSONobj, null, 2) + "\n";
-      fs.writeFileSync(__dirname + "/config.json", configString);
+      fs.writeFileSync(__dirname + "/config.json", JSON.stringify(configJSONobj, null, 2) + "\n");
       break;
     } catch (err) {
       if (i >= 2) throw err;
-      var now = Date.now();
+      const now = Date.now();
       while (Date.now() - now < 2);
     }
   }
@@ -1967,8 +1966,8 @@ function start(init) {
       }, 300000);
     } else if (cluster.isPrimary) {
       setInterval(() => {
-        var allWorkers = Object.keys(cluster.workers);
-        var goodWorkers = [];
+        let allWorkers = Object.keys(cluster.workers);
+        let goodWorkers = [];
 
         const checkWorker = (callback, _id) => {
           if (typeof _id === "undefined") _id = 0;
@@ -2058,8 +2057,8 @@ function start(init) {
             commands[line.split(" ")[0]] !== undefined &&
             commands[line.split(" ")[0]] !== null
           ) {
-            var argss = line.split(" ");
-            var command = argss.shift();
+            let argss = line.split(" ");
+            const command = argss.shift();
             commands[command](argss, (msg) => process.send(msg));
             process.send("\x12END");
           } else {
@@ -2087,15 +2086,15 @@ function start(init) {
         const command = argss.shift();
         if (line != "") {
           if (cluster.isPrimary !== undefined) {
-            var allWorkers = Object.keys(cluster.workers);
+            let allWorkers = Object.keys(cluster.workers);
             if (command == "block")
               commands.block(argss, serverconsole.climessage);
             if (command == "unblock")
               commands.unblock(argss, serverconsole.climessage);
             if (command == "restart") {
-              var stopError = false;
+              let stopError = false;
               exiting = true;
-              for (var i = 0; i < allWorkers.length; i++) {
+              for (let i = 0; i < allWorkers.length; i++) {
                 try {
                   if (cluster.workers[allWorkers[i]]) {
                     cluster.workers[allWorkers[i]].kill();
@@ -2224,7 +2223,7 @@ function start(init) {
               !process.serverConfig.secure
             ) {
               // It doesn't support through Unix sockets or Windows named pipes
-              var address = (
+              let address = (
                 typeof process.serverConfig.port == "number" && listenAddress
                   ? listenAddress
                   : "localhost"
@@ -2232,7 +2231,7 @@ function start(init) {
               if (address.indexOf(":") > -1) {
                 address = "[" + address + "]";
               }
-              var connection = http2.connect(
+              const connection = http2.connect(
                 "http://" +
                   address +
                   ":" +
diff --git a/src/middleware/nonStandardCodesAndHttpAuthentication.js b/src/middleware/nonStandardCodesAndHttpAuthentication.js
index 4f5487a..164be7f 100644
--- a/src/middleware/nonStandardCodesAndHttpAuthentication.js
+++ b/src/middleware/nonStandardCodesAndHttpAuthentication.js
@@ -29,7 +29,7 @@ let passwordHashCacheIntervalId = -1;
 // Non-standard code object
 let nonStandardCodes = [];
 process.serverConfig.nonStandardCodes.forEach((nonStandardCodeRaw) => {
-  var newObject = {};
+  let newObject = {};
   Object.keys(nonStandardCodeRaw).forEach((nsKey) => {
     if (nsKey != "users") {
       newObject[nsKey] = nonStandardCodeRaw[nsKey];
@@ -77,7 +77,7 @@ module.exports = (req, res, logFacilities, config, next) => {
         );
         if (nonStandardCodes[i].regex) {
           // Regex match
-          var createdRegex = createRegex(nonStandardCodes[i].regex, true);
+          const createdRegex = createRegex(nonStandardCodes[i].regex, true);
           isMatch =
             req.url.match(createdRegex) ||
             hrefWithoutDuplicateSlashes.match(createdRegex);
diff --git a/src/middleware/redirects.js b/src/middleware/redirects.js
index d594f73..5e02caf 100644
--- a/src/middleware/redirects.js
+++ b/src/middleware/redirects.js
@@ -9,7 +9,7 @@ module.exports = (req, res, logFacilities, config, next) => {
     !config.disableNonEncryptedServer &&
     !config.disableToHTTPSRedirect
   ) {
-    var hostx = req.headers.host;
+    const hostx = req.headers.host;
     if (hostx === undefined) {
       logFacilities.errmessage("Host header is missing.");
       res.error(400);
@@ -22,7 +22,7 @@ module.exports = (req, res, logFacilities, config, next) => {
       return;
     }
 
-    var isPublicServer = !(
+    const isPublicServer = !(
       req.socket.realRemoteAddress
         ? req.socket.realRemoteAddress
         : req.socket.remoteAddress
@@ -30,11 +30,11 @@ module.exports = (req, res, logFacilities, config, next) => {
       /^(?:localhost$|::1$|f[c-d][0-9a-f]{2}:|(?:::ffff:)?(?:(?:127|10)\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}|192\.168\.[0-9]{1,3}\.[0-9]{1,3}|172\.(?:1[6-9]|2[0-9]|3[0-1])\.[0-9]{1,3}\.[0-9]{1,3})$)/i,
     );
 
-    var destinationPort = 0;
+    let destinationPort = 0;
 
-    var parsedHostx = hostx.match(/(\[[^\]]*\]|[^:]*)(?::([0-9]+))?/);
-    var hostname = parsedHostx[1];
-    var hostPort = parsedHostx[2] ? parseInt(parsedHostx[2]) : 80;
+    const parsedHostx = hostx.match(/(\[[^\]]*\]|[^:]*)(?::([0-9]+))?/);
+    let hostname = parsedHostx[1];
+    let hostPort = parsedHostx[2] ? parseInt(parsedHostx[2]) : 80;
     if (isNaN(hostPort)) hostPort = 80;
 
     if (
diff --git a/src/middleware/responseHeaders.js b/src/middleware/responseHeaders.js
index 393c42a..db746eb 100644
--- a/src/middleware/responseHeaders.js
+++ b/src/middleware/responseHeaders.js
@@ -1,6 +1,6 @@
 module.exports = (req, res, logFacilities, config, next) => {
   if (!req.isProxy) {
-    var hkh = config.getCustomHeaders();
+    const hkh = config.getCustomHeaders();
     Object.keys(hkh).forEach((hkS) => {
       try {
         res.setHeader(hkS, hkh[hkS]);
diff --git a/src/middleware/rewriteURL.js b/src/middleware/rewriteURL.js
index c4cce0f..a11ab2d 100644
--- a/src/middleware/rewriteURL.js
+++ b/src/middleware/rewriteURL.js
@@ -30,7 +30,7 @@ module.exports = (req, res, logFacilities, config, next) => {
           fs.stat(
             "." + decodeURIComponent(req.parsedURL.pathname),
             (err, stats) => {
-              var _fileState = 3;
+              let _fileState = 3;
               if (err) {
                 _fileState = 3;
               } else if (stats.isDirectory()) {
@@ -126,7 +126,7 @@ module.exports = (req, res, logFacilities, config, next) => {
         logFacilities.errmessage("Content blocked.");
         return;
       } else if (sHref != req.parsedURL.pathname) {
-        var rewrittenAgainURL =
+        const rewrittenAgainURL =
           sHref +
           (req.parsedURL.search ? req.parsedURL.search : "") +
           (req.parsedURL.hash ? req.parsedURL.hash : "");
diff --git a/src/middleware/staticFileServingAndDirectoryListings.js b/src/middleware/staticFileServingAndDirectoryListings.js
index bea1530..d210359 100644
--- a/src/middleware/staticFileServingAndDirectoryListings.js
+++ b/src/middleware/staticFileServingAndDirectoryListings.js
@@ -34,7 +34,7 @@ module.exports = (req, res, logFacilities, config, next) => {
     let levelDownCount = 0;
 
     // Loop through the path components
-    for (var i = 0; i < pathComponents.length; i++) {
+    for (let i = 0; i < pathComponents.length; i++) {
       // If the component is "..", decrement the levelUpCount
       if (".." === pathComponents[i]) {
         levelUpCount--;
@@ -313,7 +313,7 @@ module.exports = (req, res, logFacilities, config, next) => {
           // Helper function to check if compression is allowed for the file
           const canCompress = (path, list) => {
             let canCompress = true;
-            for (var i = 0; i < list.length; i++) {
+            for (let i = 0; i < list.length; i++) {
               if (createRegex(list[i], true).test(path)) {
                 canCompress = false;
                 break;
@@ -437,7 +437,7 @@ module.exports = (req, res, logFacilities, config, next) => {
                 })
                 .on("open", () => {
                   try {
-                    var resStream = {};
+                    let resStream = {};
                     if (useBrotli && isCompressable) {
                       resStream = zlib.createBrotliCompress();
                       resStream.pipe(res);
@@ -738,7 +738,7 @@ module.exports = (req, res, logFacilities, config, next) => {
                   // Get stats for all files in the directory and generate the listing
                   getStatsForAllFiles(list, readFrom, (filelist) => {
                     let directoryListingRows = [];
-                    for (var i = 0; i < filelist.length; i++) {
+                    for (let i = 0; i < filelist.length; i++) {
                       if (filelist[i].name[0] !== ".") {
                         const estats = filelist[i].stats;
                         const ename = filelist[i].name;
diff --git a/src/utils/generateErrorStack.js b/src/utils/generateErrorStack.js
index 8451a11..24f9af4 100644
--- a/src/utils/generateErrorStack.js
+++ b/src/utils/generateErrorStack.js
@@ -1,7 +1,7 @@
 // Generate V8-style error stack from Error object.
 function generateErrorStack(errorObject) {
   // Split the error stack by newlines.
-  var errorStack = errorObject.stack ? errorObject.stack.split("\n") : [];
+  const errorStack = errorObject.stack ? errorObject.stack.split("\n") : [];
 
   // If the error stack starts with the error name, return the original stack (it is V8-style then).
   if (
@@ -13,7 +13,7 @@ function generateErrorStack(errorObject) {
   }
 
   // Create a new error stack with the error name and code (if available).
-  var newErrorStack = [
+  let newErrorStack = [
     errorObject.name +
       (errorObject.code ? ": " + errorObject.code : "") +
       (errorObject.message == "" ? "" : ": " + errorObject.message),
@@ -23,12 +23,12 @@ function generateErrorStack(errorObject) {
   errorStack.forEach((errorStackLine) => {
     if (errorStackLine != "") {
       // Split the line into function and location parts (if available).
-      var errorFrame = errorStackLine.split("@");
-      var location = "";
+      let errorFrame = errorStackLine.split("@");
+      let location = "";
       if (errorFrame.length > 1 && errorFrame[0] == "global code")
         errorFrame.shift();
       if (errorFrame.length > 1) location = errorFrame.pop();
-      var func = errorFrame.join("@");
+      const func = errorFrame.join("@");
 
       // Build the new error stack entry with function and location information.
       newErrorStack.push(
diff --git a/src/utils/getOS.js b/src/utils/getOS.js
index 7f181eb..b64c7a5 100644
--- a/src/utils/getOS.js
+++ b/src/utils/getOS.js
@@ -1,12 +1,12 @@
 const os = require("os");
 
 function getOS() {
-  var osType = os.type();
-  var platform = os.platform();
+  const osType = os.type();
+  const platform = os.platform();
   if (platform == "android") {
     return "Android";
   } else if (osType == "Windows_NT" || osType == "WindowsNT") {
-    var arch = os.arch();
+    const arch = os.arch();
     if (arch == "ia32") {
       return "Win32";
     } else if (arch == "x64") {
diff --git a/src/utils/ipBlockList.js b/src/utils/ipBlockList.js
index 2d4fda7..cdeea64 100644
--- a/src/utils/ipBlockList.js
+++ b/src/utils/ipBlockList.js
@@ -2,7 +2,7 @@
 function ipBlockList(rawBlockList) {
   // Initialize the instance with empty arrays
   if (rawBlockList === undefined) rawBlockList = [];
-  var instance = {
+  const instance = {
     raw: [],
     rawtoPreparedMap: [],
     prepared: [],
diff --git a/src/utils/ipSubnetUtils.js b/src/utils/ipSubnetUtils.js
index e2aeeeb..8a6cfcb 100644
--- a/src/utils/ipSubnetUtils.js
+++ b/src/utils/ipSubnetUtils.js
@@ -14,7 +14,7 @@ function calculateBroadcastIPv4FromCidr(ipWithCidr) {
     .split(".")
     .map((num, index) => {
       // Calculate resulting 8-bit
-      var power = Math.max(Math.min(mask - index * 8, 8), 0);
+      const power = Math.max(Math.min(mask - index * 8, 8), 0);
       return (
         (parseInt(num) & ((Math.pow(2, power) - 1) << (8 - power))) |
         (Math.pow(2, 8 - power) - 1)
@@ -39,7 +39,7 @@ function calculateNetworkIPv4FromCidr(ipWithCidr) {
     .split(".")
     .map((num, index) => {
       // Calculate resulting 8-bit
-      var power = Math.max(Math.min(mask - index * 8, 8), 0);
+      const power = Math.max(Math.min(mask - index * 8, 8), 0);
       return (
         parseInt(num) &
         ((Math.pow(2, power) - 1) << (8 - power))
diff --git a/src/utils/serverconsole.js b/src/utils/serverconsole.js
index 096ba0e..60c613e 100644
--- a/src/utils/serverconsole.js
+++ b/src/utils/serverconsole.js
@@ -78,7 +78,7 @@ function LOG(s) {
 }
 
 // Server console function
-var serverconsole = {
+const serverconsole = {
   climessage: (msg, reqId) => {
     if (msg.indexOf("\n") != -1) {
       msg.split("\n").forEach((nmsg) => {