diff --git a/src/CommandLineParser.ts b/src/CommandLineParser.ts
index 44f6b09..b1bb3cb 100644
--- a/src/CommandLineParser.ts
+++ b/src/CommandLineParser.ts
@@ -224,7 +224,7 @@ function checkQualityValue(argv: any): boolean {
 
 
 export function promptUser(choices: Array<string>): number {
-    let index: number = readlineSync.keyInSelect(choices, 'Which resolution/format do you prefer?');
+    const index: number = readlineSync.keyInSelect(choices, 'Which resolution/format do you prefer?');
 
     if (index === -1) {
         process.exit(ERROR_CODE.CANCELLED_USER_INPUT);
diff --git a/src/DownloadManager.ts b/src/DownloadManager.ts
index 6360f05..547d162 100644
--- a/src/DownloadManager.ts
+++ b/src/DownloadManager.ts
@@ -135,7 +135,7 @@ export class DownloadManager {
      * @param options object with key: value pairs
      */
     private setOptions(options: {[option: string]: string}, guid?: string): void {
-        let message: string = guid ?
+        const message: string = guid ?
             this.createMessage('aria2.changeOption', [guid, options]) :
             this.createMessage('aria2.changeGlobalOption', [options]);
 
@@ -186,7 +186,7 @@ export class DownloadManager {
                     // TODO: test download error parsing, not had a chance to yet
                     logger.error(JSON.stringify(parsed));
 
-                    let errorGid: string = parsed.params.pop().gid.toString();
+                    const errorGid: string = parsed.params.pop().gid.toString();
                     this.queue.delete(errorGid);
 
                     // TODO: add this to createMessage
diff --git a/src/Thumbnail.ts b/src/Thumbnail.ts
index aea3940..0502977 100644
--- a/src/Thumbnail.ts
+++ b/src/Thumbnail.ts
@@ -8,7 +8,7 @@ import { AxiosResponse } from 'axios';
 export async function drawThumbnail(posterImage: string, session: Session): Promise<void> {
     const apiClient: ApiClient = ApiClient.getInstance(session);
 
-    let thumbnail: Buffer = await apiClient.callUrl(posterImage, 'get', null, 'arraybuffer')
+    const thumbnail: Buffer = await apiClient.callUrl(posterImage, 'get', null, 'arraybuffer')
         .then((response: AxiosResponse<any> | undefined) => response?.data);
 
     console.log(await terminalImage.buffer(thumbnail, { width: 70 } ));
diff --git a/src/TokenCache.ts b/src/TokenCache.ts
index d46360e..db9ff37 100644
--- a/src/TokenCache.ts
+++ b/src/TokenCache.ts
@@ -19,16 +19,16 @@ export class TokenCache {
             return null;
         }
 
-        let session: Session = JSON.parse(fs.readFileSync(this.tokenCacheFile, 'utf8'));
+        const session: Session = JSON.parse(fs.readFileSync(this.tokenCacheFile, 'utf8'));
 
         type Jwt = {
             [key: string]: any
         }
         const decodedJwt: Jwt = jwtDecode(session.AccessToken);
 
-        let now: number = Math.floor(Date.now() / 1000);
-        let exp: number = decodedJwt['exp'];
-        let timeLeft: number = exp - now;
+        const now: number = Math.floor(Date.now() / 1000);
+        const exp: number = decodedJwt['exp'];
+        const timeLeft: number = exp - now;
 
         if (timeLeft < 120) {
             logger.warn('Access token has expired! \n');
@@ -42,7 +42,7 @@ export class TokenCache {
     }
 
     public Write(session: Session): void {
-        let s: string = JSON.stringify(session, null, 4);
+        const s: string = JSON.stringify(session, null, 4);
         fs.writeFile('.token_cache', s, (err: any) => {
             if (err) {
                 return logger.error(err);
diff --git a/src/Utils.ts b/src/Utils.ts
index 910c9e8..15346b2 100644
--- a/src/Utils.ts
+++ b/src/Utils.ts
@@ -23,7 +23,7 @@ async function extractGuids(url: string, client: ApiClient): Promise<Array<strin
         const videoNumber: number = await client.callApi(`groups/${groupMatch[1]}`, 'get')
             .then((response: AxiosResponse<any> | undefined) => response?.data.metrics.videos);
 
-        let result: Array<string> = await client.callApi(`groups/${groupMatch[1]}/videos?$top=${videoNumber}&$orderby=publishedDate asc`, 'get')
+        const result: Array<string> = await client.callApi(`groups/${groupMatch[1]}/videos?$top=${videoNumber}&$orderby=publishedDate asc`, 'get')
             .then((response: AxiosResponse<any> | undefined) => response?.data.value.map((item: any) => item.id));
 
         return result;
@@ -48,7 +48,7 @@ export async function parseCLIinput(urlList: Array<string>, defaultOutDir: strin
     session: Session): Promise<Array<Array<string>>> {
 
     const apiClient: ApiClient = ApiClient.getInstance(session);
-    let guidList: Array<string> = [];
+    const guidList: Array<string> = [];
 
     for (const url of urlList) {
         const guids: Array<string> | null = await extractGuids(url, apiClient);
@@ -85,8 +85,8 @@ export async function parseInputFile(inputFile: string, defaultOutDir: string,
         .split(/\r?\n/);
     const apiClient: ApiClient = ApiClient.getInstance(session);
 
-    let guidList: Array<string> = [];
-    let outDirList: Array<string> = [];
+    const guidList: Array<string> = [];
+    const outDirList: Array<string> = [];
     // if the last line was an url set this
     let foundUrl = false;
 
@@ -101,7 +101,7 @@ export async function parseInputFile(inputFile: string, defaultOutDir: string,
         // parse if line is option
         else if (line.includes('-dir')) {
             if (foundUrl) {
-                let outDir: string | null = parseOption('-dir', line);
+                const outDir: string | null = parseOption('-dir', line);
 
                 if (outDir && checkOutDir(outDir)) {
                     outDirList.push(...Array(guidList.length - outDirList.length)
diff --git a/src/VideoUtils.ts b/src/VideoUtils.ts
index 804b1b2..5524f28 100644
--- a/src/VideoUtils.ts
+++ b/src/VideoUtils.ts
@@ -39,7 +39,7 @@ function isoDurationToString(time: string): string {
 export async function getVideosInfo(videoGuids: Array<string>,
     session: Session, subtitles?: boolean): Promise<Array<Video>> {
 
-    let metadata: Array<Video> = [];
+    const metadata: Array<Video> = [];
 
     let title: string;
     let duration: string;
@@ -60,7 +60,7 @@ export async function getVideosInfo(videoGuids: Array<string>,
     MSS servers or we get throttled after 10 sequential reqs */
     for (const guid of videoGuids) {
 
-        let response: AxiosResponse<any> | undefined =
+        const response: AxiosResponse<any> | undefined =
             await apiClient.callApi('videos/' + guid + '?$expand=creator', 'get');
 
         title = sanitizeWindowsName(response?.data['name']);
@@ -87,7 +87,7 @@ export async function getVideosInfo(videoGuids: Array<string>,
         posterImageUrl = response?.data['posterImage']['medium']['url'];
 
         if (subtitles) {
-            let captions: AxiosResponse<any> | undefined = await apiClient.callApi(`videos/${guid}/texttracks`, 'get');
+            const captions: AxiosResponse<any> | undefined = await apiClient.callApi(`videos/${guid}/texttracks`, 'get');
 
             if (!captions?.data.value.length) {
                 captionsUrl = undefined;
@@ -137,7 +137,7 @@ export function createUniquePaths(videos: Array<Video>, outDirs: Array<string>,
         let match = elementRegEx.exec(template);
 
         while (match) {
-            let value = video[match[1] as keyof Video] as string;
+            const value = video[match[1] as keyof Video] as string;
             title = title.replace(match[0], value);
             match = elementRegEx.exec(template);
         }
diff --git a/src/destreamer.ts b/src/destreamer.ts
index 5936712..793f7b8 100644
--- a/src/destreamer.ts
+++ b/src/destreamer.ts
@@ -201,7 +201,7 @@ async function downloadVideo(videoGUIDs: Array<string>,
 
         // video playlist url
         let videoPlaylistUrl: string;
-        let videoPlaylists: Array<any> = (masterParser.manifest.playlists as Array<any>)
+        const videoPlaylists: Array<any> = (masterParser.manifest.playlists as Array<any>)
             .filter(playlist =>
                 Object.prototype.hasOwnProperty.call(playlist.attributes, 'RESOLUTION'));
 
@@ -227,9 +227,10 @@ async function downloadVideo(videoGUIDs: Array<string>,
 
         // audio playlist url
         // TODO: better audio playlists parsing? With language maybe?
-        let audioPlaylistUrl: string;
-        let audioPlaylists: Array<string> = Object.keys(masterParser.manifest.mediaGroups.AUDIO.audio);
-        audioPlaylistUrl = masterParser.manifest.mediaGroups.AUDIO.audio[audioPlaylists[0]].uri;
+        const audioPlaylists: Array<string> =
+            Object.keys(masterParser.manifest.mediaGroups.AUDIO.audio);
+        const audioPlaylistUrl: string =
+            masterParser.manifest.mediaGroups.AUDIO.audio[audioPlaylists[0]].uri;
         // if (audioPlaylists.length === 1){
         //     audioPlaylistUrl = masterParser.manifest.mediaGroups.AUDIO
         //         .audio[audioPlaylists[0]].uri;
@@ -342,8 +343,9 @@ async function downloadVideo(videoGUIDs: Array<string>,
 async function main(): Promise<void> {
     await init(); // must be first
 
-    let session: Session;
-    session = tokenCache.Read() ?? await DoInteractiveLogin('https://web.microsoftstream.com/', argv.username);
+
+    const session: Session = tokenCache.Read() ??
+        await DoInteractiveLogin('https://web.microsoftstream.com/', argv.username);
 
     logger.verbose('Session and API info \n' +
         '\t API Gateway URL: '.cyan + session.ApiGatewayUri + '\n' +