diff --git a/.vscode/settings.json b/.vscode/settings.json
index d5aad171..c2bfbbdd 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -9,5 +9,6 @@
     "cSpell.words": [
       "Retryable",
       "typecheck"
-    ]
+    ],
+    "typescript.tsdk": "./node_modules/typescript/lib"
 }
diff --git a/packages/auth/vite-legacy.config.ts b/packages/auth/vite-legacy.config.ts
index 257b31d2..35c2d9e0 100644
--- a/packages/auth/vite-legacy.config.ts
+++ b/packages/auth/vite-legacy.config.ts
@@ -1,9 +1,13 @@
 import topLevelAwait from 'vite-plugin-top-level-await';
-import { defineConfig, mergeConfig } from 'vitest/config';
+import {
+  type UserConfigFnObject,
+  defineConfig,
+  mergeConfig,
+} from 'vitest/config';
 
 import defaultViteConfig from './vite.config';
 
-export default defineConfig(configEnv =>
+const config: UserConfigFnObject = defineConfig(configEnv =>
   mergeConfig(
     defaultViteConfig(configEnv),
     defineConfig({
@@ -20,3 +24,5 @@ export default defineConfig(configEnv =>
     }),
   ),
 );
+
+export default config;
diff --git a/packages/auth/vite.config.ts b/packages/auth/vite.config.ts
index e824abc5..2d402c73 100644
--- a/packages/auth/vite.config.ts
+++ b/packages/auth/vite.config.ts
@@ -1,7 +1,11 @@
 import dts from 'vite-plugin-dts';
-import { type UserConfig, defineConfig } from 'vitest/config';
+import {
+  type UserConfig,
+  type UserConfigFnObject,
+  defineConfig,
+} from 'vitest/config';
 
-export default defineConfig(({ command }) => {
+const config: UserConfigFnObject = defineConfig(({ command }) => {
   // needed for demo cors
   const serverExtras: UserConfig =
     command === 'serve'
@@ -49,3 +53,5 @@ export default defineConfig(({ command }) => {
     ...serverExtras,
   };
 });
+
+export default config;
diff --git a/packages/common/tsconfig.json b/packages/common/tsconfig.json
index a8ed344e..84ca2fd5 100644
--- a/packages/common/tsconfig.json
+++ b/packages/common/tsconfig.json
@@ -1,7 +1,9 @@
 {
   "extends": "../../tsconfig.json",
   "compilerOptions": {
-    "baseUrl": "."
+    "baseUrl": ".",
+    "declaration": true,
+    "isolatedDeclarations": true
   },
   "include": ["."]
 }
diff --git a/packages/common/vite.config.ts b/packages/common/vite.config.ts
index ecbc7fc6..2b929455 100644
--- a/packages/common/vite.config.ts
+++ b/packages/common/vite.config.ts
@@ -1,7 +1,7 @@
 import dts from 'vite-plugin-dts';
-import { configDefaults, defineConfig } from 'vitest/config';
+import { configDefaults, defineConfig, type UserConfig } from 'vitest/config';
 
-export default defineConfig({
+const config: UserConfig = defineConfig({
   build: {
     lib: {
       entry: 'src/index.ts',
@@ -28,3 +28,5 @@ export default defineConfig({
     unstubGlobals: true,
   },
 });
+
+export default config;
diff --git a/packages/player/src/api/event/active-device-disconnected.ts b/packages/player/src/api/event/active-device-disconnected.ts
index e73ebfda..f3597749 100644
--- a/packages/player/src/api/event/active-device-disconnected.ts
+++ b/packages/player/src/api/event/active-device-disconnected.ts
@@ -3,6 +3,6 @@ export const eventName = 'active-device-disconnected';
 /**
  * Native player device disconnect event.
  */
-export function activeDeviceDisconnected() {
+export function activeDeviceDisconnected(): CustomEvent {
   return new CustomEvent(eventName);
 }
diff --git a/packages/player/src/api/event/preload-request.ts b/packages/player/src/api/event/preload-request.ts
index 948e29d5..c7f85eb6 100644
--- a/packages/player/src/api/event/preload-request.ts
+++ b/packages/player/src/api/event/preload-request.ts
@@ -1,3 +1,3 @@
-export function preloadRequest() {
+export function preloadRequest(): CustomEvent {
   return new CustomEvent('preload-request');
 }
diff --git a/packages/player/src/config.ts b/packages/player/src/config.ts
index 95d1131d..75ecde34 100644
--- a/packages/player/src/config.ts
+++ b/packages/player/src/config.ts
@@ -44,4 +44,4 @@ export function update(updates: Partial<Config>): Config {
   return state;
 }
 
-export const events = new EventTarget();
+export const events: EventTarget = new EventTarget();
diff --git a/packages/player/src/event-bus.ts b/packages/player/src/event-bus.ts
index f328d067..a9d02996 100644
--- a/packages/player/src/event-bus.ts
+++ b/packages/player/src/event-bus.ts
@@ -1,7 +1,7 @@
 import { PlayerError } from './internal';
 
 class PlayerEventTarget extends EventTarget {
-  dispatchError(error: PlayerError) {
+  dispatchError(error: PlayerError): void {
     this.dispatchEvent(
       new CustomEvent('error', {
         detail: error.toJSON(),
@@ -10,4 +10,4 @@ class PlayerEventTarget extends EventTarget {
   }
 }
 
-export const events = new PlayerEventTarget();
+export const events: PlayerEventTarget = new PlayerEventTarget();
diff --git a/packages/player/src/index.ts b/packages/player/src/index.ts
index c4c91d6d..00e4a1f8 100644
--- a/packages/player/src/index.ts
+++ b/packages/player/src/index.ts
@@ -44,7 +44,7 @@ export function getMediaElement(): HTMLMediaElement | null {
  *
  * @param {Options} options
  */
-export function bootstrap(options: Options) {
+export function bootstrap(options: Options): void {
   playerState.activePlayer = undefined;
 
   if (options.outputDevices === true) {
diff --git a/packages/player/src/internal/beacon/index.ts b/packages/player/src/internal/beacon/index.ts
index cac386ef..3f19209b 100644
--- a/packages/player/src/internal/beacon/index.ts
+++ b/packages/player/src/internal/beacon/index.ts
@@ -9,7 +9,7 @@ import type { CommitData, PrematureEvents } from './types';
  * Generates a Web Worker from a function.
  */
 // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
-export function workerize(method: Function) {
+export function workerize(method: Function): string {
   const functionBody = `(${method.toString()})();`;
   const workerBlob = new Blob([functionBody], { type: 'text/javascript' });
 
@@ -34,7 +34,7 @@ async function handleWorkerMessage(
 /**
  * Start the event beacon worker.
  */
-export async function start() {
+export async function start(): Promise<void> {
   if (!worker) {
     const { beacon } = await import('./worker');
 
@@ -54,7 +54,7 @@ function notEmpty<TValue>(value: TValue | null | undefined): value is TValue {
 export async function commit(
   beaconWorker: Worker | undefined,
   data: Pick<CommitData, 'events' | 'type'>,
-) {
+): Promise<CommitData | undefined> {
   if (beaconWorker) {
     const finishedEvents = await Promise.all(data.events);
     const definedEvents: Array<PrematureEvents> =
@@ -86,4 +86,6 @@ export async function commit(
   } else {
     console.warn('Event beacon is not running.');
   }
+
+  return undefined;
 }
diff --git a/packages/player/src/internal/beacon/worker.ts b/packages/player/src/internal/beacon/worker.ts
index 74a403e3..c0cd75a3 100644
--- a/packages/player/src/internal/beacon/worker.ts
+++ b/packages/player/src/internal/beacon/worker.ts
@@ -34,7 +34,7 @@ type Sessions = {
   userId: number;
 };
 
-export function beacon() {
+export function beacon(): void {
   let queue: Array<BeaconEvent> = [];
   let accessToken: string | undefined;
   let clientId: string | undefined;
diff --git a/packages/player/src/internal/event-tracking/play-log/index.ts b/packages/player/src/internal/event-tracking/play-log/index.ts
index b6ae895f..ebeb2970 100644
--- a/packages/player/src/internal/event-tracking/play-log/index.ts
+++ b/packages/player/src/internal/event-tracking/play-log/index.ts
@@ -28,7 +28,7 @@ export function mapProductTypeToPlayLogProductType(
 /**
  * Send event to event system scoped to play_log category.
  */
-export function commit(data: Pick<CommitData, 'events'>) {
+export function commit(data: Pick<CommitData, 'events'>): Promise<CommitData> {
   return runIfAuthorizedWithUser(() =>
     beaconCommit(worker, {
       type: 'play_log' as const,
diff --git a/packages/player/src/internal/event-tracking/play-log/playback-session.ts b/packages/player/src/internal/event-tracking/play-log/playback-session.ts
index b6985eb5..5c9e9759 100644
--- a/packages/player/src/internal/event-tracking/play-log/playback-session.ts
+++ b/packages/player/src/internal/event-tracking/play-log/playback-session.ts
@@ -1,4 +1,4 @@
-import { createReducer } from '../../helpers/reducer';
+import { createReducer, type Reducer } from '../../helpers/reducer';
 import type {
   AssetPresentation,
   AudioMode,
@@ -55,7 +55,7 @@ const defaultPayload: Payload = {
   startTimestamp: -1,
 };
 
-const reducer = await createReducer<Payload, 'playback_session'>(
+const reducer: Reducer<Payload, 'playback_session'> = await createReducer(
   'playback_session',
   defaultPayload,
 );
@@ -71,14 +71,22 @@ const reducer = await createReducer<Payload, 'playback_session'>(
  * of media for a certain media product has been presented
  * to the user.
  */
-export function playbackSession(newData: Parameters<typeof reducer>[0]) {
+export function playbackSession(newData: Parameters<typeof reducer>[0]): Promise<{
+  payload: Payload;
+  name: "playback_session";
+  streamingSessionId: string;
+} | undefined> {
   return reducer(newData);
 }
 
 export function playbackSessionAction(
   streamingSessionId: string,
   action: Action,
-) {
+): Promise<{
+  payload: Payload;
+  name: "playback_session";
+  streamingSessionId: string;
+} | undefined> {
   return reducer({
     actions: [action],
     streamingSessionId,
diff --git a/packages/player/src/internal/event-tracking/streaming-metrics/drm-license-fetch.ts b/packages/player/src/internal/event-tracking/streaming-metrics/drm-license-fetch.ts
index 52e857e4..c66319e5 100644
--- a/packages/player/src/internal/event-tracking/streaming-metrics/drm-license-fetch.ts
+++ b/packages/player/src/internal/event-tracking/streaming-metrics/drm-license-fetch.ts
@@ -1,4 +1,4 @@
-import { createReducer } from '../../helpers/reducer';
+import { createReducer, type Reducer } from '../../helpers/reducer';
 
 export type Payload = {
   endReason: 'COMPLETE' | 'ERROR' | 'OTHER';
@@ -23,11 +23,15 @@ const defaultPayload: Payload = {
   streamingSessionId: '',
 };
 
-const reducer = await createReducer<Payload, 'drm_license_fetch'>(
+const reducer: Reducer<Payload, 'drm_license_fetch'> = await createReducer(
   'drm_license_fetch',
   defaultPayload,
 );
 
-export function drmLicenseFetch(newData: Parameters<typeof reducer>[0]) {
+export function drmLicenseFetch(newData: Parameters<typeof reducer>[0]): Promise<{
+  payload: Payload;
+  name: "drm_license_fetch";
+  streamingSessionId: string;
+} | undefined> {
   return reducer(newData);
 }
diff --git a/packages/player/src/internal/event-tracking/streaming-metrics/index.ts b/packages/player/src/internal/event-tracking/streaming-metrics/index.ts
index dc0e3fb0..fe68760c 100644
--- a/packages/player/src/internal/event-tracking/streaming-metrics/index.ts
+++ b/packages/player/src/internal/event-tracking/streaming-metrics/index.ts
@@ -1,6 +1,6 @@
 export { drmLicenseFetch } from './drm-license-fetch';
 export { playbackInfoFetch } from './playback-info-fetch';
-export { playbackStatistics } from './playback-statistics';
+export { playbackStatisticsTrack, playbackStatisticsVideo, playbackStatistics } from './playback-statistics';
 export { streamingSessionEnd } from './streaming-session-end';
 export { streamingSessionStart } from './streaming-session-start';
 
@@ -11,7 +11,7 @@ import { runIfAuthorizedWithUser } from '../../helpers/run-if-authorized-with-us
 /**
  * Send event to event system scoped to streaming_metrics category.
  */
-export function commit(data: Pick<CommitData, 'events'>) {
+export function commit(data: Pick<CommitData, 'events'>): Promise<CommitData> {
   return runIfAuthorizedWithUser(() =>
     beaconCommit(worker, {
       type: 'streaming_metrics',
diff --git a/packages/player/src/internal/event-tracking/streaming-metrics/playback-info-fetch.ts b/packages/player/src/internal/event-tracking/streaming-metrics/playback-info-fetch.ts
index 275b0c87..aacb754e 100644
--- a/packages/player/src/internal/event-tracking/streaming-metrics/playback-info-fetch.ts
+++ b/packages/player/src/internal/event-tracking/streaming-metrics/playback-info-fetch.ts
@@ -1,4 +1,4 @@
-import { createReducer } from '../../helpers/reducer';
+import { createReducer, type Reducer } from '../../helpers/reducer';
 
 export type Payload = {
   endReason: 'COMPLETE' | 'ERROR' | 'OTHER';
@@ -23,7 +23,7 @@ const defaultPayload: Payload = {
   streamingSessionId: '',
 };
 
-const reducer = await createReducer<Payload, 'playback_info_fetch'>(
+const reducer: Reducer<Payload, 'playback_info_fetch'> = await createReducer(
   'playback_info_fetch',
   defaultPayload,
 );
@@ -31,6 +31,10 @@ const reducer = await createReducer<Payload, 'playback_info_fetch'>(
 /**
  * Create playbackInfoFetch event.
  */
-export function playbackInfoFetch(newData: Parameters<typeof reducer>[0]) {
+export function playbackInfoFetch(newData: Parameters<typeof reducer>[0]): Promise<{
+  payload: Payload;
+  name: "playback_info_fetch";
+  streamingSessionId: string;
+} | undefined> {
   return reducer(newData);
 }
diff --git a/packages/player/src/internal/event-tracking/streaming-metrics/playback-statistics.ts b/packages/player/src/internal/event-tracking/streaming-metrics/playback-statistics.ts
index 7e9d9c4d..557e813a 100644
--- a/packages/player/src/internal/event-tracking/streaming-metrics/playback-statistics.ts
+++ b/packages/player/src/internal/event-tracking/streaming-metrics/playback-statistics.ts
@@ -1,4 +1,4 @@
-import { createReducer } from '../../helpers/reducer';
+import { createReducer, type Reducer } from '../../helpers/reducer';
 import type { OutputType } from '../../output-devices';
 import type { AudioQuality, VideoQuality } from '../../types';
 
@@ -48,21 +48,19 @@ export type BasePayload = {
   streamingSessionId: string;
 };
 
-export type TrackPayload = {
-  actualQuality: AudioQuality;
-  productType: 'TRACK';
-};
-
-export type VideoPayload = {
+export type VideoPayload = BasePayload & {
   actualQuality: VideoQuality;
   productType: 'VIDEO';
 };
 
-export type Payload = BasePayload & (TrackPayload | VideoPayload);
+export type TrackPayload = BasePayload & {
+  actualQuality: AudioQuality;
+  productType: 'TRACK';
+};
 
 export type PlaybackStatistics = {
   name: 'playback_statistics';
-  payload: Payload;
+  payload: TrackPayload | VideoPayload;
 };
 
 export function transformOutputType(
@@ -89,7 +87,7 @@ export function transformOutputType(
   }
 }
 
-const defaultPayload: Payload = {
+const defaultTrackPayload: TrackPayload = {
   actualAssetPresentation: 'FULL',
   actualAudioMode: 'STEREO',
   actualProductId: null,
@@ -111,14 +109,69 @@ const defaultPayload: Payload = {
   streamingSessionId: '',
 };
 
-const reducer = await createReducer<Payload, 'playback_statistics'>(
+const defaultVideoPayload: VideoPayload = {
+  actualAssetPresentation: 'FULL',
+  actualAudioMode: 'STEREO',
+  actualProductId: null,
+  actualQuality: 'HIGH',
+  actualStartTimestamp: 0,
+  actualStreamType: 'ON_DEMAND',
+  adaptations: [],
+  cdm: 'WIDEVINE',
+  cdmVersion: null,
+  endReason: 'COMPLETE',
+  endTimestamp: 0,
+  errorCode: null,
+  errorMessage: null,
+  hasAds: false,
+  idealStartTimestamp: 0,
+  outputDevice: null,
+  productType: 'VIDEO',
+  stalls: [],
+  streamingSessionId: '',
+};
+
+const reducer: Reducer<TrackPayload, "playback_statistics"> = await createReducer(
   'playback_statistics',
-  defaultPayload,
+  defaultTrackPayload,
 );
 
 /**
  * Create playbackStatistics event.
  */
-export function playbackStatistics(newData: Parameters<typeof reducer>[0]) {
+export function playbackStatistics(newData: Parameters<typeof reducer>[0]): Promise<{
+  payload: TrackPayload | VideoPayload;
+  name: "playback_statistics";
+  streamingSessionId: string;
+} | undefined> {
   return reducer(newData);
 }
+
+const trackPayloadReducer: Reducer<TrackPayload, "playback_statistics"> = await createReducer(
+  'playback_statistics',
+  defaultTrackPayload,
+);
+
+/**
+ * Create playbackStatistics event.
+ */
+export function playbackStatisticsTrack(newData: Parameters<typeof trackPayloadReducer>[0]): Promise<{
+  payload: TrackPayload;
+  name: "playback_statistics";
+  streamingSessionId: string;
+} | undefined> {
+  return trackPayloadReducer(newData);
+}
+
+const videoPayloadReducer: Reducer<VideoPayload, "playback_statistics"> = await createReducer(
+  'playback_statistics',
+  defaultVideoPayload,
+);
+
+export function playbackStatisticsVideo(newData: Parameters<typeof videoPayloadReducer>[0]): Promise<{
+  payload: VideoPayload;
+  name: "playback_statistics";
+  streamingSessionId: string;
+} | undefined> {
+  return videoPayloadReducer(newData);
+}
diff --git a/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-end.ts b/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-end.ts
index ff053c78..751bd213 100644
--- a/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-end.ts
+++ b/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-end.ts
@@ -1,4 +1,4 @@
-import { createReducer } from '../../helpers/reducer';
+import { createReducer, type Reducer } from '../../helpers/reducer';
 
 export type Payload = {
   streamingSessionId: string;
@@ -15,7 +15,7 @@ const defaultPayload: Payload = {
   timestamp: 0,
 };
 
-const reducer = await createReducer<Payload, 'streaming_session_end'>(
+const reducer: Reducer<Payload, 'streaming_session_end'> = await createReducer(
   'streaming_session_end',
   defaultPayload,
 );
@@ -24,6 +24,10 @@ const reducer = await createReducer<Payload, 'streaming_session_end'>(
  * The streaming session end event is sent by clients once a streaming session
  * ends, for whatever reason. It represents the end of a streaming session.
  */
-export function streamingSessionEnd(newData: Parameters<typeof reducer>[0]) {
+export function streamingSessionEnd(newData: Parameters<typeof reducer>[0]): Promise<{
+  payload: Payload;
+  name: "streaming_session_end";
+  streamingSessionId: string;
+} | undefined> {
   return reducer(newData);
 }
diff --git a/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-start.ts b/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-start.ts
index 6f90c4a6..7f68dfc7 100644
--- a/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-start.ts
+++ b/packages/player/src/internal/event-tracking/streaming-metrics/streaming-session-start.ts
@@ -1,6 +1,6 @@
 import Bowser from 'bowser';
 
-import { createReducer } from '../../helpers/reducer';
+import { createReducer, type Reducer } from '../../helpers/reducer';
 
 const platform = Bowser.parse(navigator.userAgent);
 
@@ -53,7 +53,7 @@ const defaultPayload: Payload = {
   timestamp: 0,
 };
 
-const reducer = await createReducer<Payload, 'streaming_session_start'>(
+const reducer: Reducer<Payload, 'streaming_session_start'> = await createReducer(
   'streaming_session_start',
   defaultPayload,
 );
@@ -68,6 +68,10 @@ const reducer = await createReducer<Payload, 'streaming_session_start'>(
  * A new streaming session starts whenever a client
  * decides that a media asset should be played.
  */
-export function streamingSessionStart(newData: Parameters<typeof reducer>[0]) {
+export function streamingSessionStart(newData: Parameters<typeof reducer>[0]): Promise<{
+  payload: Payload;
+  name: "streaming_session_start";
+  streamingSessionId: string;
+} | undefined> {
   return reducer(newData);
 }
diff --git a/packages/player/src/internal/handlers/get-asset-position.ts b/packages/player/src/internal/handlers/get-asset-position.ts
index aca36e78..35e5cf73 100644
--- a/packages/player/src/internal/handlers/get-asset-position.ts
+++ b/packages/player/src/internal/handlers/get-asset-position.ts
@@ -6,7 +6,7 @@ import { playerState } from '../../player/state';
  *
  * @returns {number}
  */
-export function getAssetPosition() {
+export function getAssetPosition(): number {
   const player = playerState.activePlayer;
 
   return player?.getPosition() ?? 0;
diff --git a/packages/player/src/internal/handlers/get-output-devices.ts b/packages/player/src/internal/handlers/get-output-devices.ts
index d36a2656..471db540 100644
--- a/packages/player/src/internal/handlers/get-output-devices.ts
+++ b/packages/player/src/internal/handlers/get-output-devices.ts
@@ -1,9 +1,11 @@
+import type { OutputDevice } from '../../internal/output-devices';
+
 /**
  * Get the available output devices.
  *
- * @returns { Set<OutputDevice>}
+ * @returns {Array<OutputDevice>}
  */
-export async function getOutputDevices() {
+export async function getOutputDevices(): Promise<Array<OutputDevice>> {
   const { outputDevices } = await import('../../internal/output-devices');
 
   return [...outputDevices.outputDevices];
diff --git a/packages/player/src/internal/handlers/get-volume-level.ts b/packages/player/src/internal/handlers/get-volume-level.ts
index 537b51b6..3874989a 100644
--- a/packages/player/src/internal/handlers/get-volume-level.ts
+++ b/packages/player/src/internal/handlers/get-volume-level.ts
@@ -5,6 +5,6 @@ import * as Config from '../../config';
  *
  * @returns {number}
  */
-export function getVolumeLevel() {
+export function getVolumeLevel(): number {
   return Config.get('desiredVolumeLevel');
 }
diff --git a/packages/player/src/internal/handlers/load.ts b/packages/player/src/internal/handlers/load.ts
index 3842606c..9701fba0 100644
--- a/packages/player/src/internal/handlers/load.ts
+++ b/packages/player/src/internal/handlers/load.ts
@@ -35,7 +35,7 @@ export async function load(
   mediaProduct: MediaProduct,
   assetPosition = 0,
   prefetch = false,
-) {
+): Promise<void> {
   await trueTime.synchronize();
 
   Pushkin.ensure().catch(console.error);
diff --git a/packages/player/src/internal/handlers/pause.ts b/packages/player/src/internal/handlers/pause.ts
index 749f125d..b5524111 100644
--- a/packages/player/src/internal/handlers/pause.ts
+++ b/packages/player/src/internal/handlers/pause.ts
@@ -7,6 +7,6 @@ import { playerState } from '../../player/state';
  *
  * @see {@link import('../../api/event/playback-state-change').PlaybackStateChange}
  */
-export function pause() {
+export function pause(): void {
   return playerState.activePlayer?.pause();
 }
diff --git a/packages/player/src/internal/handlers/play.ts b/packages/player/src/internal/handlers/play.ts
index adb18bb7..7153b378 100644
--- a/packages/player/src/internal/handlers/play.ts
+++ b/packages/player/src/internal/handlers/play.ts
@@ -13,7 +13,7 @@ import { trueTime } from '../true-time';
  * @returns {Promise<void>}
  * @see {@link import('../../api/event/playback-state-change').PlaybackStateChange}
  */
-export async function play() {
+export async function play(): Promise<void> {
   await trueTime.synchronize();
 
   const { activePlayer: player } = playerState;
diff --git a/packages/player/src/internal/handlers/reset.ts b/packages/player/src/internal/handlers/reset.ts
index 7a441d98..29313e9e 100644
--- a/packages/player/src/internal/handlers/reset.ts
+++ b/packages/player/src/internal/handlers/reset.ts
@@ -13,7 +13,7 @@ import ConnectionHandler from '../services/connection-handler';
  * @returns {Promise<void>}
  * @see {@link import('../../api/event/playback-state-change').PlaybackStateChange}
  */
-export async function reset() {
+export async function reset(): Promise<void> {
   cancelQueuedOnendedHandler();
   ConnectionHandler.disable();
 
diff --git a/packages/player/src/internal/handlers/seek.ts b/packages/player/src/internal/handlers/seek.ts
index 8fac7787..ea763e85 100644
--- a/packages/player/src/internal/handlers/seek.ts
+++ b/packages/player/src/internal/handlers/seek.ts
@@ -5,7 +5,7 @@ import { playerState } from '../../player/state';
  *
  * @param {number} time - seconds
  */
-export async function seek(time: number) {
+export async function seek(time: number): Promise<number | void> {
   const { activePlayer: player } = playerState;
 
   return player?.seek(time);
diff --git a/packages/player/src/internal/handlers/set-api-url.ts b/packages/player/src/internal/handlers/set-api-url.ts
index e77b74b9..4642133a 100644
--- a/packages/player/src/internal/handlers/set-api-url.ts
+++ b/packages/player/src/internal/handlers/set-api-url.ts
@@ -5,7 +5,7 @@ import * as Config from '../../config';
  *
  * @param {string} apiUrl
  */
-export function setApiUrl(apiUrl: string) {
+export function setApiUrl(apiUrl: string): void {
   // eslint-disable-next-line no-useless-catch
   try {
     new URL(apiUrl);
diff --git a/packages/player/src/internal/handlers/set-app-version.ts b/packages/player/src/internal/handlers/set-app-version.ts
index ed534833..b32ca414 100644
--- a/packages/player/src/internal/handlers/set-app-version.ts
+++ b/packages/player/src/internal/handlers/set-app-version.ts
@@ -7,7 +7,7 @@ import * as Config from '../../config';
  *
  * @param {string} appVersion
  */
-export function setAppVersion(appVersion: string) {
+export function setAppVersion(appVersion: string): void {
   Config.update({
     appVersion,
   });
diff --git a/packages/player/src/internal/handlers/set-client-platform.ts b/packages/player/src/internal/handlers/set-client-platform.ts
index 2f13ce96..8abf9b37 100644
--- a/packages/player/src/internal/handlers/set-client-platform.ts
+++ b/packages/player/src/internal/handlers/set-client-platform.ts
@@ -7,7 +7,7 @@ import * as Config from '../../config';
  *
  * @param {string} clientPlatform
  */
-export function setClientPlatform(clientPlatform: string) {
+export function setClientPlatform(clientPlatform: string): void {
   Config.update({
     clientPlatform,
   });
diff --git a/packages/player/src/internal/handlers/set-credentials-provider.ts b/packages/player/src/internal/handlers/set-credentials-provider.ts
index 1fa8915e..7135d3a7 100644
--- a/packages/player/src/internal/handlers/set-credentials-provider.ts
+++ b/packages/player/src/internal/handlers/set-credentials-provider.ts
@@ -10,6 +10,6 @@ import { credentialsProviderStore } from '../index';
  */
 export function setCredentialsProvider(
   newCredentialsProvider: CredentialsProvider,
-) {
+): void {
   credentialsProviderStore.credentialsProvider = newCredentialsProvider;
 }
diff --git a/packages/player/src/internal/handlers/set-event-url.ts b/packages/player/src/internal/handlers/set-event-url.ts
index 2222c3c0..f32c839f 100644
--- a/packages/player/src/internal/handlers/set-event-url.ts
+++ b/packages/player/src/internal/handlers/set-event-url.ts
@@ -5,7 +5,7 @@ import * as Config from '../../config';
  *
  * @param {string} eventUrl
  */
-export function setEventUrl(eventUrl: string) {
+export function setEventUrl(eventUrl: string): void {
   // eslint-disable-next-line no-useless-catch
   try {
     new URL(eventUrl);
diff --git a/packages/player/src/internal/handlers/set-loudness-normalization-mode.ts b/packages/player/src/internal/handlers/set-loudness-normalization-mode.ts
index f1f19bf9..c8dad806 100644
--- a/packages/player/src/internal/handlers/set-loudness-normalization-mode.ts
+++ b/packages/player/src/internal/handlers/set-loudness-normalization-mode.ts
@@ -7,7 +7,7 @@ import { playerState } from '../../player/state';
  *
  * @param {LoudnessNormalizationMode} mode
  */
-export function setLoudnessNormalizationMode(mode: LoudnessNormalizationMode) {
+export function setLoudnessNormalizationMode(mode: LoudnessNormalizationMode): void {
   Config.update({
     loudnessNormalizationMode: mode,
   });
diff --git a/packages/player/src/internal/handlers/set-next.ts b/packages/player/src/internal/handlers/set-next.ts
index 98a83aa5..68233bff 100644
--- a/packages/player/src/internal/handlers/set-next.ts
+++ b/packages/player/src/internal/handlers/set-next.ts
@@ -31,7 +31,7 @@ export let latestNextCall: {
 async function _setNext(
   mediaProduct?: MediaProduct,
   sessionTags: Array<string> = [],
-) {
+): Promise<void> {
   cancelQueuedOnendedHandler();
 
   // If next handler is called with undefined/null as media product, we treat that as an unset.
@@ -184,7 +184,7 @@ async function _setNext(
 export function setNext(
   mediaProduct?: MediaProduct,
   sessionTags: Array<string> = [],
-) {
+): Promise<void> {
   /**
    * If next has already been called with the same media product,
    * return that promise instead of fetching playback info and
diff --git a/packages/player/src/internal/handlers/set-streaming-wifi-audio-quality.ts b/packages/player/src/internal/handlers/set-streaming-wifi-audio-quality.ts
index b263d1d3..3b9fa76a 100644
--- a/packages/player/src/internal/handlers/set-streaming-wifi-audio-quality.ts
+++ b/packages/player/src/internal/handlers/set-streaming-wifi-audio-quality.ts
@@ -8,7 +8,7 @@ import type { AudioQuality } from '../../internal/types';
  */
 export function setStreamingWifiAudioQuality(
   streamingWifiAudioQuality: AudioQuality,
-) {
+): void {
   Config.update({
     streamingWifiAudioQuality,
   });
diff --git a/packages/player/src/internal/handlers/set-volume-level.ts b/packages/player/src/internal/handlers/set-volume-level.ts
index 51417da8..ce3c9f61 100644
--- a/packages/player/src/internal/handlers/set-volume-level.ts
+++ b/packages/player/src/internal/handlers/set-volume-level.ts
@@ -6,7 +6,7 @@ import * as Config from '../../config';
  *
  * @param {number} desiredVolumeLevel
  */
-export function setVolumeLevel(desiredVolumeLevel: number) {
+export function setVolumeLevel(desiredVolumeLevel: number): void {
   Config.update({
     desiredVolumeLevel,
   });
diff --git a/packages/player/src/internal/handlers/start-native-player.ts b/packages/player/src/internal/handlers/start-native-player.ts
index 5ed2fbe8..430afa7f 100644
--- a/packages/player/src/internal/handlers/start-native-player.ts
+++ b/packages/player/src/internal/handlers/start-native-player.ts
@@ -3,7 +3,7 @@ import { getNativePlayer, setActivePlayer } from '../../player/index';
 /**
  * Start native player before playback to access output devices.
  */
-export async function startNativePlayer() {
+export async function startNativePlayer(): Promise<void> {
   const nativePlayer = await getNativePlayer();
 
   setActivePlayer(nativePlayer);
diff --git a/packages/player/src/internal/helpers/event-session.ts b/packages/player/src/internal/helpers/event-session.ts
index f18318c6..cc99d6d3 100644
--- a/packages/player/src/internal/helpers/event-session.ts
+++ b/packages/player/src/internal/helpers/event-session.ts
@@ -80,4 +80,4 @@ class EventSessionDB {
   }
 }
 
-export const db = new EventSessionDB();
+export const db: EventSessionDB = new EventSessionDB();
diff --git a/packages/player/src/internal/helpers/on.ts b/packages/player/src/internal/helpers/on.ts
index b98cb018..53eaa663 100644
--- a/packages/player/src/internal/helpers/on.ts
+++ b/packages/player/src/internal/helpers/on.ts
@@ -1,4 +1,4 @@
-export function on(target: EventTarget, eventName: string) {
+export function on(target: EventTarget, eventName: string): Promise<Event> {
   return new Promise(resolve => {
     target.addEventListener(eventName, event => resolve(event), { once: true });
   });
diff --git a/packages/player/src/internal/helpers/playback-info-resolver.ts b/packages/player/src/internal/helpers/playback-info-resolver.ts
index a5e80813..5563393a 100644
--- a/packages/player/src/internal/helpers/playback-info-resolver.ts
+++ b/packages/player/src/internal/helpers/playback-info-resolver.ts
@@ -282,7 +282,7 @@ export function getDemoPlaybackInfo(options: Options): PlaybackInfo {
   };
 }
 
-export async function fetchPlaybackInfo(options: Options) {
+export async function fetchPlaybackInfo(options: Options): Promise<PlaybackInfo> {
   const { streamingSessionId } = options;
   const events = [];
 
@@ -312,7 +312,7 @@ export async function fetchPlaybackInfo(options: Options) {
     const hasAds = 'adInfo' in playbackInfo;
 
     if ('trackId' in playbackInfo) {
-      StreamingMetrics.playbackStatistics({
+      StreamingMetrics.playbackStatisticsTrack({
         actualAssetPresentation: playbackInfo.assetPresentation,
         actualAudioMode: playbackInfo.audioMode,
         actualProductId: String(playbackInfo.trackId),
@@ -322,8 +322,8 @@ export async function fetchPlaybackInfo(options: Options) {
         productType: 'TRACK',
         streamingSessionId,
       }).catch(console.error);
-    } else {
-      StreamingMetrics.playbackStatistics({
+    } else if ('videoId' in playbackInfo) {
+      StreamingMetrics.playbackStatisticsVideo({
         actualAssetPresentation: playbackInfo.assetPresentation,
         actualAudioMode: undefined,
         actualProductId: String(playbackInfo.videoId),
@@ -333,6 +333,8 @@ export async function fetchPlaybackInfo(options: Options) {
         productType: 'VIDEO',
         streamingSessionId,
       }).catch(console.error);
+    } else {
+      console.error('No trackId or videoId in playback info.');
     }
 
     performance.mark('streaming_metrics:playback_info_fetch:endTimestamp', {
diff --git a/packages/player/src/internal/helpers/reducer.ts b/packages/player/src/internal/helpers/reducer.ts
index 790ac1f2..ebe12e1b 100644
--- a/packages/player/src/internal/helpers/reducer.ts
+++ b/packages/player/src/internal/helpers/reducer.ts
@@ -2,10 +2,16 @@ import * as Config from '../../config';
 
 import { db } from './event-session';
 
+export type Reducer<P, N extends string> = (newData: { streamingSessionId: string } & Partial<P>) => Promise<{
+  payload: P,
+  name: N,
+  streamingSessionId: string,
+} | undefined>;
+
 export async function createReducer<P, N extends string>(
   name: N,
   defaultPayload: P,
-) {
+): Promise<Reducer<P, N>> {
   if (!Config.get('gatherEvents')) {
     // @ts-expect-error - Not used
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
@@ -52,6 +58,8 @@ export async function createReducer<P, N extends string>(
       };
     } catch (e) {
       console.error(e);
+
+      return undefined;
     }
   };
 }
diff --git a/packages/player/src/internal/helpers/run-if-authorized-with-user.ts b/packages/player/src/internal/helpers/run-if-authorized-with-user.ts
index 52319c4a..168ec059 100644
--- a/packages/player/src/internal/helpers/run-if-authorized-with-user.ts
+++ b/packages/player/src/internal/helpers/run-if-authorized-with-user.ts
@@ -4,7 +4,7 @@ import { isAuthorizedWithUser } from '../index';
  * Run the provided function if we're authorized with a user.
  */
 // eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
-export async function runIfAuthorizedWithUser(fn: Function) {
+export async function runIfAuthorizedWithUser(fn: Function): Promise<any> {
   const authorizedWithUser = await isAuthorizedWithUser();
 
   if (authorizedWithUser) {
diff --git a/packages/player/src/internal/helpers/streaming-session-store.ts b/packages/player/src/internal/helpers/streaming-session-store.ts
index 425c085f..2549e38d 100644
--- a/packages/player/src/internal/helpers/streaming-session-store.ts
+++ b/packages/player/src/internal/helpers/streaming-session-store.ts
@@ -18,7 +18,7 @@ class StreamingSessionStore {
    * @param from - streamingSessionId to clone
    * @param to - target streamingSessionId
    */
-  clone(from: string, to: string) {
+  clone(from: string, to: string): void {
     const mediaProductTransition = this.getMediaProductTransition(from);
     const streamInfo = this.getStreamInfo(from);
     const playbackInfo = this.getPlaybackInfo(from);
@@ -46,7 +46,7 @@ class StreamingSessionStore {
     });
   }
 
-  deleteMediaProductTransition(streamingSessionId: string) {
+  deleteMediaProductTransition(streamingSessionId: string): void {
     this.#mediaProductTransitions.delete(streamingSessionId);
   }
 
@@ -56,18 +56,18 @@ class StreamingSessionStore {
    *
    * @see {@link StreamingSessionStore.clone}
    */
-  deleteSession(streamingSessionId: string) {
+  deleteSession(streamingSessionId: string): void {
     this.deleteMediaProductTransition(streamingSessionId);
     this.#playbackInfos.delete(streamingSessionId);
     this.#startedStreamInfos.delete(streamingSessionId);
     this.deleteStreamInfo(streamingSessionId);
   }
 
-  deleteStartedStreamInfo(streamingSessionId: string) {
+  deleteStartedStreamInfo(streamingSessionId: string): void {
     this.#startedStreamInfos.delete(streamingSessionId);
   }
 
-  deleteStreamInfo(streamingSessionId: string) {
+  deleteStreamInfo(streamingSessionId: string): void {
     this.#streamInfos.delete(streamingSessionId);
   }
 
@@ -95,23 +95,23 @@ class StreamingSessionStore {
       : undefined;
   }
 
-  hasMediaProductTransition(streamingSessionId: string) {
+  hasMediaProductTransition(streamingSessionId: string): boolean {
     return this.#mediaProductTransitions.has(streamingSessionId);
   }
 
-  hasPlaybackInfo(streamingSessionId: string) {
+  hasPlaybackInfo(streamingSessionId: string): boolean {
     return this.#playbackInfos.has(streamingSessionId);
   }
 
-  hasStartedStreamInfo(streamingSessionId: string) {
+  hasStartedStreamInfo(streamingSessionId: string): boolean {
     return this.#startedStreamInfos.has(streamingSessionId);
   }
 
-  hasStreamInfo(streamingSessionId: string) {
+  hasStreamInfo(streamingSessionId: string): boolean {
     return this.#streamInfos.has(streamingSessionId);
   }
 
-  overwriteDuration(streamingSessionId: string, updatedDuration: number) {
+  overwriteDuration(streamingSessionId: string, updatedDuration: number): void {
     const mediaProductTransition =
       this.#mediaProductTransitions.get(streamingSessionId);
 
@@ -130,18 +130,18 @@ class StreamingSessionStore {
   saveMediaProductTransition(
     streamingSessionId: string,
     mediaProductTransition: MediaProductTransitionPayload,
-  ) {
+  ): void {
     this.#mediaProductTransitions.set(
       streamingSessionId,
       mediaProductTransition,
     );
   }
 
-  savePlaybackInfo(streamingSessionId: string, streamInfo: PlaybackInfo) {
+  savePlaybackInfo(streamingSessionId: string, streamInfo: PlaybackInfo): void {
     this.#playbackInfos.set(streamingSessionId, streamInfo);
   }
 
-  saveStreamInfo(streamingSessionId: string, streamInfo: StreamInfo) {
+  saveStreamInfo(streamingSessionId: string, streamInfo: StreamInfo): void {
     this.#streamInfos.set(streamingSessionId, streamInfo);
   }
 
@@ -150,4 +150,4 @@ class StreamingSessionStore {
   }
 }
 
-export const streamingSessionStore = new StreamingSessionStore();
+export const streamingSessionStore: StreamingSessionStore = new StreamingSessionStore();
diff --git a/packages/player/src/internal/helpers/string-similarity.ts b/packages/player/src/internal/helpers/string-similarity.ts
index 26fe6557..953dab97 100644
--- a/packages/player/src/internal/helpers/string-similarity.ts
+++ b/packages/player/src/internal/helpers/string-similarity.ts
@@ -34,7 +34,11 @@ function compareTwoStrings(first: string, second: string) {
 export function findBestMatch(
   mainString: string,
   targetStrings: Array<string>,
-) {
+): {
+  bestMatch: { rating: number; target: string } | undefined;
+  bestMatchIndex: number;
+  ratings: Array<{ rating: number; target: string }>;
+} {
   if (!areArgsValid(mainString, targetStrings)) {
     throw new Error(
       'Bad arguments: First argument should be a string, second should be an array of strings',
diff --git a/packages/player/src/internal/helpers/wait-for-players.ts b/packages/player/src/internal/helpers/wait-for-players.ts
index bba8cc49..f223df78 100644
--- a/packages/player/src/internal/helpers/wait-for-players.ts
+++ b/packages/player/src/internal/helpers/wait-for-players.ts
@@ -12,7 +12,7 @@ const handler = (
   }
 };
 
-export function waitForPlayers() {
+export function waitForPlayers(): Promise<void | void[]> {
   const playerRoot = document.getElementById('tidal-player-root');
 
   if (!playerRoot) {
diff --git a/packages/player/src/internal/helpers/wait-for.ts b/packages/player/src/internal/helpers/wait-for.ts
index ab87d63f..ee9f81ff 100644
--- a/packages/player/src/internal/helpers/wait-for.ts
+++ b/packages/player/src/internal/helpers/wait-for.ts
@@ -1,9 +1,9 @@
-export function waitFor(ms: number) {
+export function waitFor(ms: number): Promise<void> {
   // setTimeout are garbage collected on a "this" basis.
   return new Promise<void>(resolve => setTimeout(() => resolve(), ms));
 }
 
-export function waitForEvent(target: EventTarget, eventName: string) {
+export function waitForEvent(target: EventTarget, eventName: string): Promise<Event> {
   return new Promise(resolve => {
     target.addEventListener(eventName, event => resolve(event), false);
   });
diff --git a/packages/player/src/internal/index.ts b/packages/player/src/internal/index.ts
index a15c9808..ad130422 100644
--- a/packages/player/src/internal/index.ts
+++ b/packages/player/src/internal/index.ts
@@ -9,7 +9,7 @@ class CredentialsProviderStore extends EventTarget {
   // @ts-ignore - Setter
   #credentialsProvider: CredentialsProvider;
 
-  async dispatchAuthorized() {
+  async dispatchAuthorized(): Promise<void> {
     const credentials = await this.#credentialsProvider.getCredentials();
 
     if (credentials?.token) {
@@ -207,7 +207,11 @@ export class PlayerError extends Error {
     this.referenceId = referenceId;
   }
 
-  toJSON() {
+  toJSON(): {
+    errorCode: ErrorCodes | null,
+    errorId: ErrorIds | null,
+    referenceId: string | undefined,
+  } {
     return {
       errorCode: this.errorCode,
       errorId: this.errorId,
@@ -215,7 +219,7 @@ export class PlayerError extends Error {
     };
   }
 
-  toString() {
+  toString(): string {
     return JSON.stringify(this.toJSON());
   }
 }
@@ -226,7 +230,7 @@ export class PlayerError extends Error {
  *
  * @returns {Promise<boolean>}
  */
-export async function isAuthorizedWithUser() {
+export async function isAuthorizedWithUser(): Promise<boolean> {
   if (credentialsProviderStore.credentialsProvider) {
     const credentials =
       await credentialsProviderStore.credentialsProvider.getCredentials();
@@ -239,7 +243,7 @@ export async function isAuthorizedWithUser() {
   return isAuthorizedWithUser();
 }
 
-export const credentialsProviderStore = new CredentialsProviderStore();
+export const credentialsProviderStore: CredentialsProviderStore = new CredentialsProviderStore();
 
 /**
  * Starts streaming privileges and event code if the credentials allow it.
@@ -285,7 +289,7 @@ credentialsProviderStore.addEventListener('authorized', () => {
  * Returns null if credentials provider is not set up or
  * if the token is undefined.
  */
-export async function getAccessToken() {
+export async function getAccessToken(): Promise<string | null> {
   if (credentialsProviderStore.credentialsProvider) {
     const credentials =
       await credentialsProviderStore.credentialsProvider.getCredentials();
diff --git a/packages/player/src/internal/output-devices.ts b/packages/player/src/internal/output-devices.ts
index 053451e5..65402693 100644
--- a/packages/player/src/internal/output-devices.ts
+++ b/packages/player/src/internal/output-devices.ts
@@ -110,7 +110,7 @@ export function findOutputType(
   return undefined;
 }
 
-export function marshalLabel(deviceLabel: string, operatingSystem: string) {
+export function marshalLabel(deviceLabel: string, operatingSystem: string): string {
   const osName = operatingSystem.toLowerCase();
   let nicerLabel = deviceLabel;
 
@@ -141,7 +141,7 @@ export function isWindowsCommunicationsDevice(
 export function getOutputDeviceByName(
   devices: Set<OutputDevice>,
   name: string,
-) {
+): OutputDevice | undefined {
   name = marshalLabel(name, platform.os.name || '');
 
   if ([...devices].length === 0 || name === '') {
@@ -226,7 +226,7 @@ export class OutputDevices {
     }) as EventListener);
   }
 
-  addNativeDevices(devices: Array<NativePlayerComponentDeviceDescription>) {
+  addNativeDevices(devices: Array<NativePlayerComponentDeviceDescription>): void {
     this.#events.dispatchEvent(
       new CustomEvent('native-devices', {
         detail: devices,
@@ -234,7 +234,7 @@ export class OutputDevices {
     );
   }
 
-  addWebDevices(devices: Array<MediaDeviceInfo>) {
+  addWebDevices(devices: Array<MediaDeviceInfo>): void {
     // Filter out the default device.
     devices = devices.filter(d => d.deviceId !== 'default');
 
@@ -245,7 +245,7 @@ export class OutputDevices {
     );
   }
 
-  emitDeviceChange() {
+  emitDeviceChange(): void {
     events.dispatchEvent(deviceChange([...this.outputDevices]));
   }
 
@@ -255,14 +255,14 @@ export class OutputDevices {
     return [...this.#nativeDevices].find(nd => nd.id === id);
   }
 
-  async hydrateWebDevices() {
+  async hydrateWebDevices(): Promise<void> {
     const mediaDevices = await navigator.mediaDevices.enumerateDevices();
     const audioOutputs = mediaDevices.filter(d => d.kind === 'audiooutput');
 
     this.addWebDevices(audioOutputs);
   }
 
-  mergeDevices() {
+  mergeDevices(): void {
     // Remove previous native and web IDs for non-default devices
     // but keep the names and id.
     [...this.outputDevices]
@@ -327,7 +327,7 @@ export class OutputDevices {
       .forEach(od => this.outputDevices.delete(od));
   }
 
-  async queueUpdate() {
+  async queueUpdate(): Promise<void> {
     const nativeDeviceChange = new Promise<
       Array<NativePlayerComponentDeviceDescription>
     >(resolve =>
@@ -390,4 +390,4 @@ export class OutputDevices {
   }
 }
 
-export const outputDevices = new OutputDevices();
+export const outputDevices: OutputDevices = new OutputDevices();
diff --git a/packages/player/src/internal/services/connection-handler.ts b/packages/player/src/internal/services/connection-handler.ts
index 071d2223..6b54b440 100644
--- a/packages/player/src/internal/services/connection-handler.ts
+++ b/packages/player/src/internal/services/connection-handler.ts
@@ -92,7 +92,7 @@ export default class ConnectionHandler {
     }
   }
 
-  static disable() {
+  static disable(): void {
     if (this.#enabled) {
       if (this.#offlineHandler) {
         window.removeEventListener('offline', this.#offlineHandler, false);
@@ -108,7 +108,7 @@ export default class ConnectionHandler {
     }
   }
 
-  static enable() {
+  static enable(): void {
     if (!this.#enabled) {
       this.#onlineHandler = () => this.#handleOnline();
       this.#offlineHandler = () => this.#handleOffline();
diff --git a/packages/player/src/internal/services/pushkin.ts b/packages/player/src/internal/services/pushkin.ts
index 33e06e3b..317029a4 100644
--- a/packages/player/src/internal/services/pushkin.ts
+++ b/packages/player/src/internal/services/pushkin.ts
@@ -48,7 +48,7 @@ let pushkin: Pushkin | undefined;
 
 // Only exported for testing.
 // eslint-disable-next-line disable-autofix/jsdoc/require-jsdoc
-export async function fetchWebSocketURL(accessToken: string) {
+export async function fetchWebSocketURL(accessToken: string): Promise<string> {
   const apiUrl = Config.get('apiUrl');
   const response = await fetch(apiUrl + '/rt/connect', {
     headers: new Headers({
@@ -69,7 +69,7 @@ export async function fetchWebSocketURL(accessToken: string) {
 
 // Only exported for testing.
 // eslint-disable-next-line disable-autofix/jsdoc/require-jsdoc
-export function socketOpen(webSocket: WebSocket) {
+export function socketOpen(webSocket: WebSocket): Promise<void> {
   return new Promise<void>(resolve => {
     webSocket.addEventListener('open', () => resolve(), { once: true });
   });
@@ -104,7 +104,7 @@ export class Pushkin {
   /**
    * Call this method to ensure pushkin is running.
    */
-  static async ensure() {
+  static async ensure(): Promise<void> {
     const allowed = await isAuthorizedWithUser();
 
     if (!allowed) {
@@ -121,7 +121,7 @@ export class Pushkin {
   /**
    * Call this method when credentials changes to re-setup pushkin with the new credentials
    */
-  static async refresh() {
+  static async refresh(): Promise<void>{
     const allowed = await isAuthorizedWithUser();
 
     if (!allowed) {
@@ -226,7 +226,7 @@ export class Pushkin {
    * Call this method to tell Pushkin a user action happened, so it can
    * make good qualified guesses if you're the session with allowed playback-
    */
-  async userAction() {
+  async userAction(): Promise<void> {
     if (!this.connected) {
       await this.reconnect();
     }
@@ -243,7 +243,7 @@ export class Pushkin {
     }
   }
 
-  get connected() {
+  get connected(): boolean | undefined {
     return this.#socket && this.#socket.readyState === WebSocket.OPEN;
   }
 }
diff --git a/packages/player/src/player/adaptations.test.ts b/packages/player/src/player/adaptations.test.ts
index f7603bb0..50c9960b 100644
--- a/packages/player/src/player/adaptations.test.ts
+++ b/packages/player/src/player/adaptations.test.ts
@@ -36,7 +36,7 @@ describe('saveAdaptation', () => {
       activeShakaTrack,
       1337,
     );
-    const event = await StreamingMetrics.playbackStatistics({
+    const event = await StreamingMetrics.playbackStatisticsVideo({
       streamingSessionId: 'jeremy-session',
     });
 
diff --git a/packages/player/src/player/adaptations.ts b/packages/player/src/player/adaptations.ts
index 47d32725..0e28b1bc 100644
--- a/packages/player/src/player/adaptations.ts
+++ b/packages/player/src/player/adaptations.ts
@@ -36,7 +36,7 @@ export async function saveAdaptation(
   const adaptation = shakaTrackToAdaptation(activeTrack, currentTime);
 
   if (adaptation.mimeType && adaptation.codecs) {
-    await StreamingMetrics.playbackStatistics({
+    await StreamingMetrics.playbackStatisticsVideo({
       adaptations: [adaptation],
       streamingSessionId,
     });
@@ -77,7 +77,7 @@ export function registerAdaptations(shakaPlayer: shaka.Player) {
 
   events.addEventListener('media-product-transition', onMediaProductTransition);
 
-  return function unregister() {
+  return function unregister(): void {
     shakaPlayer.removeEventListener('adaptation', onAdaptation);
     shakaPlayer.removeEventListener('variantchanged', onAdaptation);
     events.removeEventListener(
diff --git a/packages/player/src/player/audio-context-store.ts b/packages/player/src/player/audio-context-store.ts
index 4d71890a..e813c26b 100644
--- a/packages/player/src/player/audio-context-store.ts
+++ b/packages/player/src/player/audio-context-store.ts
@@ -1,6 +1,6 @@
 import { waitForPlayers } from '../internal/helpers/wait-for-players';
 
-export const mediaElementOne = document.createElement('video');
+export const mediaElementOne: HTMLVideoElement = document.createElement('video');
 
 const prepareMediaElement = (mediaEl: HTMLMediaElement) => {
   mediaEl.setAttribute('crossorigin', 'anonymous');
@@ -12,7 +12,7 @@ mediaElementOne.id = 'video-one';
 
 const tidalPlayerRootId = 'tidal-player-root';
 
-export function mountVideoElements() {
+export function mountVideoElements(): Promise<void | void[]> {
   let templateEl = document.getElementById(tidalPlayerRootId);
 
   if (!templateEl) {
@@ -26,7 +26,7 @@ export function mountVideoElements() {
   return ensureVideoElementsMounted();
 }
 
-export function ensureVideoElementsMounted() {
+export function ensureVideoElementsMounted(): Promise<void | void[]> {
   const templateEl = document.getElementById(
     tidalPlayerRootId,
   ) as HTMLTemplateElement | null;
@@ -40,8 +40,8 @@ export function ensureVideoElementsMounted() {
   return waitForPlayers();
 }
 
-export function activateVideoElements() {
-  return new Promise<void>(resolve =>
+export function activateVideoElements(): Promise<void> {
+  return new Promise(resolve =>
     document.addEventListener(
       'click',
       () => {
diff --git a/packages/player/src/player/basePlayer.ts b/packages/player/src/player/basePlayer.ts
index 3e647f78..9b6306b5 100644
--- a/packages/player/src/player/basePlayer.ts
+++ b/packages/player/src/player/basePlayer.ts
@@ -158,7 +158,7 @@ export class BasePlayer {
   }
 
   // Implements
-  attachPlaybackEngineEndedHandler() {
+  attachPlaybackEngineEndedHandler(): void {
     if (!this.#endedHandler) {
       this.#endedHandler = this.playbackEngineEndedHandler.bind(this);
       // TS is weird with CustomEvent event listeners.
@@ -174,7 +174,7 @@ export class BasePlayer {
    * for preloadedStreamingSessionId if it does not match
    * currentStreamingSessionId.
    */
-  cleanUpStoredPreloadInfo() {
+  cleanUpStoredPreloadInfo(): void {
     if (
       this.preloadedStreamingSessionId &&
       this.preloadedStreamingSessionId !== this.currentStreamingSessionId
@@ -185,7 +185,7 @@ export class BasePlayer {
   }
 
   // Implements
-  debugLog(...args: Array<unknown>) {
+  debugLog(...args: Array<unknown>): void {
     if (
       document.location.href.includes('localhost') &&
       document.location.hash.includes('debug')
@@ -221,7 +221,7 @@ export class BasePlayer {
     }
   }
 
-  detachPlaybackEngineEndedHandler() {
+  detachPlaybackEngineEndedHandler(): void {
     if (this.#endedHandler) {
       // TS is weird with CustomEvent event listeners.
       events.removeEventListener(
@@ -246,7 +246,7 @@ export class BasePlayer {
       endAssetPosition: number;
       endReason: EndReason;
     },
-  ) {
+  ): void {
     const endTimestamp = trueTime.now();
 
     PlayLog.commit({
@@ -274,7 +274,7 @@ export class BasePlayer {
     }).catch(console.error);
   }
 
-  eventTrackingStreamingStarted(streamingSessionId: string) {
+  eventTrackingStreamingStarted(streamingSessionId: string): void {
     if (!streamingSessionId) {
       return;
     }
@@ -374,7 +374,7 @@ export class BasePlayer {
     }).catch(console.error);
   }
 
-  finishCurrentMediaProduct(endReason: EndReason) {
+  finishCurrentMediaProduct(endReason: EndReason): void {
     // A media product was loaded but never started.
     if (!this.hasStarted()) {
       return;
@@ -406,7 +406,7 @@ export class BasePlayer {
   /**
    * Refetches playbackinfo.
    */
-  async hardReload(mediaProduct: MediaProduct, assetPosition: number) {
+  async hardReload(mediaProduct: MediaProduct, assetPosition: number): Promise<void> {
     if (this.currentStreamingSessionId) {
       this.finishCurrentMediaProduct('skip');
     }
@@ -414,19 +414,19 @@ export class BasePlayer {
     return load(mediaProduct, assetPosition);
   }
 
-  hasNextItem() {
-    return this.preloadedStreamingSessionId;
+  hasNextItem(): boolean {
+    return Boolean(this.preloadedStreamingSessionId);
   }
 
-  hasStarted() {
-    return (
+  hasStarted(): boolean {
+    return Boolean(
       this.currentStreamingSessionId &&
       streamingSessionStore.hasStartedStreamInfo(this.currentStreamingSessionId)
     );
   }
 
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  load(_lp: LoadPayload, _transition: 'explicit' | 'implicit') {
+  load(_lp: LoadPayload, _transition: 'explicit' | 'implicit'): Promise<void> {
     return Promise.resolve();
   }
 
@@ -435,7 +435,7 @@ export class BasePlayer {
    *
    * @returns {boolean} True if hard reloaded, else false.
    */
-  async maybeHardReload() {
+  async maybeHardReload(): Promise<boolean> {
     // Not the same as OR in an if statement.
     // eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
     const prefetchedOrExpired = this.prefetched || this.expired;
@@ -455,7 +455,7 @@ export class BasePlayer {
    *
    * @param streamingSessionId
    */
-  mediaProductStarted(streamingSessionId: string | undefined) {
+  mediaProductStarted(streamingSessionId: string | undefined): void {
     if (
       !streamingSessionId ||
       streamingSessionStore.hasStartedStreamInfo(streamingSessionId)
@@ -477,7 +477,7 @@ export class BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  next(_lp: LoadPayload) {
+  next(_lp: LoadPayload): Promise<void> {
     return Promise.resolve();
   }
 
@@ -492,7 +492,7 @@ export class BasePlayer {
   overwriteMediaProduct(
     streamingSessionId: string,
     partialMediaProduct: Partial<MediaProduct>,
-  ) {
+  ): void {
     const oldMediaProductTransition =
       streamingSessionStore.getMediaProductTransition(streamingSessionId);
 
@@ -516,30 +516,30 @@ export class BasePlayer {
     }
   }
 
-  pause() {}
+  pause(): void {}
 
-  play() {
+  play(): Promise<void> {
     return Promise.resolve();
   }
 
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  playbackEngineEndedHandler(_e: EndedEvent) {
+  playbackEngineEndedHandler(_e: EndedEvent): Promise<void> {
     return Promise.resolve();
   }
 
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  reset(_options: { keepPreload: boolean }) {
+  reset(_options: { keepPreload: boolean }): Promise<void> {
     return Promise.resolve();
   }
 
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  seek(_number: number) {}
+  seek(_number: number): void {}
 
   /**
    * Handle play log reporting for seeking.
    * Seek start should log a PLAYBACK_START action if playing post seek.
    */
-  seekEnd(assetPosition: number) {
+  seekEnd(assetPosition: number): void {
     const streamingSessionId = this.currentStreamingSessionId;
 
     if (streamingSessionId) {
@@ -575,7 +575,7 @@ export class BasePlayer {
    * Handle play log reporting for seeking.
    * Seek start should log a PLAYBACK_STOP action.
    */
-  seekStart(assetPosition: number) {
+  seekStart(assetPosition: number): void {
     if (this.currentStreamingSessionId) {
       PlayLog.playbackSessionAction(this.currentStreamingSessionId, {
         actionType: 'PLAYBACK_STOP',
@@ -589,7 +589,7 @@ export class BasePlayer {
     ms: number,
     ifNotState: PlaybackState,
     setToState: PlaybackState,
-  ) {
+  ): Promise<void> {
     await waitFor(ms);
 
     if (this.playbackState !== ifNotState) {
@@ -597,15 +597,15 @@ export class BasePlayer {
     }
   }
 
-  skipToPreloadedMediaProduct() {
+  skipToPreloadedMediaProduct(): Promise<void> {
     return Promise.resolve();
   }
 
-  unloadPreloadedMediaProduct() {
+  unloadPreloadedMediaProduct(): Promise<void> {
     return Promise.resolve();
   }
 
-  updateOutputDevice() {
+  updateOutputDevice(): Promise<void> {
     return Promise.resolve();
   }
 
@@ -614,7 +614,7 @@ export class BasePlayer {
    * it before setting, if loudness normalization is
    * enabled.
    */
-  updateVolumeLevel() {
+  updateVolumeLevel(): void {
     const streamInfo = streamingSessionStore.getStreamInfo(
       this.currentStreamingSessionId,
     );
@@ -630,7 +630,7 @@ export class BasePlayer {
    * Adjusts the volume for the next track.
    * Can be called on product ended to have the level ready.
    */
-  updateVolumeLevelForNextProduct() {
+  updateVolumeLevelForNextProduct(): void {
     const streamInfo = streamingSessionStore.getStreamInfo(
       this.preloadedStreamingSessionId,
     );
@@ -640,7 +640,7 @@ export class BasePlayer {
     } // else: Will be adjusted on start instead.
   }
 
-  get currentMediaProduct() {
+  get currentMediaProduct(): MediaProduct | null {
     return (
       streamingSessionStore.getMediaProductTransition(
         this.currentStreamingSessionId,
@@ -665,7 +665,7 @@ export class BasePlayer {
     return this.#currentTime;
   }
 
-  get duration() {
+  get duration(): number | null {
     const mtp = streamingSessionStore.getMediaProductTransition(
       this.currentStreamingSessionId,
     );
@@ -677,7 +677,7 @@ export class BasePlayer {
     return null;
   }
 
-  get expired() {
+  get expired(): boolean {
     const streamInfo = streamingSessionStore.getStreamInfo(
       this.currentStreamingSessionId,
     );
@@ -690,13 +690,13 @@ export class BasePlayer {
     return streamInfo.expires <= Date.now();
   }
 
-  get isActivePlayer() {
+  get isActivePlayer(): boolean | undefined {
     return (
       playerState.activePlayer && this.name === playerState.activePlayer.name
     );
   }
 
-  get nextItem() {
+  get nextItem(): MediaProductTransitionPayload | undefined {
     if (this.preloadedStreamingSessionId) {
       return streamingSessionStore.getMediaProductTransition(
         this.preloadedStreamingSessionId,
@@ -768,12 +768,12 @@ export class BasePlayer {
     return this.#playbackState;
   }
 
-  get prefetched() {
+  get prefetched(): boolean {
     const streamInfo = streamingSessionStore.getStreamInfo(
       this.currentStreamingSessionId,
     );
 
-    return streamInfo?.prefetched;
+    return Boolean(streamInfo?.prefetched);
   }
 
   set preloadedStreamingSessionId(ssi: string | undefined) {
diff --git a/packages/player/src/player/browserPlayer.ts b/packages/player/src/player/browserPlayer.ts
index 4e1a79d3..d980c139 100644
--- a/packages/player/src/player/browserPlayer.ts
+++ b/packages/player/src/player/browserPlayer.ts
@@ -20,7 +20,7 @@ export default class BrowserPlayer extends BasePlayer {
   #instanceOne: HTMLVideoElement;
   #isReset = true;
 
-  #librariesLoad: Promise<void> | undefined;
+  #librariesLoad: Promise<void> = Promise.resolve();
 
   #mediaElementEventHandlers: {
     durationChangeHandler: EventListener;
@@ -199,7 +199,7 @@ export default class BrowserPlayer extends BasePlayer {
     );
   }
 
-  getPosition() {
+  getPosition(): number {
     this.debugLog('getPosition');
 
     if (this.mediaElement) {
@@ -213,7 +213,7 @@ export default class BrowserPlayer extends BasePlayer {
     return this.currentTime;
   }
 
-  async load(payload: LoadPayload, transition: 'explicit' | 'implicit') {
+  async load(payload: LoadPayload, transition: 'explicit' | 'implicit'): Promise<void> {
     this.debugLog('load', payload);
 
     this.currentTime = payload.assetPosition;
@@ -295,7 +295,7 @@ export default class BrowserPlayer extends BasePlayer {
     return Promise.resolve();
   }
 
-  async next(payload: LoadPayload) {
+  async next(payload: LoadPayload): Promise<void> {
     this.debugLog('next', payload);
 
     /*
@@ -350,7 +350,7 @@ export default class BrowserPlayer extends BasePlayer {
     this.#isReset = false;
   }
 
-  pause() {
+  pause(): void {
     this.debugLog('pause');
 
     if (this.mediaElement) {
@@ -358,7 +358,7 @@ export default class BrowserPlayer extends BasePlayer {
     }
   }
 
-  async play() {
+  async play(): Promise<void> {
     this.debugLog('play');
 
     await this.maybeHardReload();
@@ -385,7 +385,7 @@ export default class BrowserPlayer extends BasePlayer {
     }
   }
 
-  async playbackEngineEndedHandler(e: EndedEvent) {
+  async playbackEngineEndedHandler(e: EndedEvent): Promise<void> {
     if (this.isActivePlayer) {
       const { reason } = e.detail;
 
@@ -403,7 +403,7 @@ export default class BrowserPlayer extends BasePlayer {
 
   async reset(
     { keepPreload }: { keepPreload: boolean } = { keepPreload: false },
-  ) {
+  ): Promise<void> {
     if (this.#isReset) {
       return Promise.resolve();
     }
@@ -439,14 +439,14 @@ export default class BrowserPlayer extends BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/no-misused-promises
-  seek(currentTime: number) {
+  seek(currentTime: number): Promise<number> {
     this.debugLog('seek', currentTime);
 
     const { currentPlayer: mediaEl } = this;
     const seconds = currentTime;
 
     if (!mediaEl) {
-      return;
+      return Promise.resolve(0);
     }
 
     this.seekStart(this.currentTime);
@@ -466,7 +466,7 @@ export default class BrowserPlayer extends BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/require-await
-  async skipToPreloadedMediaProduct() {
+  async skipToPreloadedMediaProduct(): Promise<void> {
     const mediaProductTransition =
       streamingSessionStore.getMediaProductTransition(
         this.preloadedStreamingSessionId,
@@ -500,7 +500,7 @@ export default class BrowserPlayer extends BasePlayer {
     }
   }
 
-  togglePlayback() {
+  togglePlayback(): void {
     this.debugLog('togglePlayback');
 
     if (this.mediaElement) {
@@ -513,7 +513,7 @@ export default class BrowserPlayer extends BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/require-await
-  async unloadPreloadedMediaProduct() {
+  async unloadPreloadedMediaProduct(): Promise<void> {
     this.debugLog(
       'unloadPreloadedMediaProduct',
       this.preloadedStreamingSessionId,
@@ -551,7 +551,7 @@ export default class BrowserPlayer extends BasePlayer {
     return this.currentPlayer ?? null;
   }
 
-  get ready() {
+  get ready(): Promise<void> {
     return this.#librariesLoad;
   }
 
diff --git a/packages/player/src/player/fairplay-drm.ts b/packages/player/src/player/fairplay-drm.ts
index 572c0358..8256565b 100644
--- a/packages/player/src/player/fairplay-drm.ts
+++ b/packages/player/src/player/fairplay-drm.ts
@@ -1,7 +1,7 @@
 /**
  * Certificate loading logic:
  */
-export async function loadServerCertificate() {
+export async function loadServerCertificate(): Promise<Uint8Array> {
   try {
     const response = await fetch(
       'https://resources.tidal.com/drm/fairplay/certificate',
diff --git a/packages/player/src/player/filters.ts b/packages/player/src/player/filters.ts
index f7243e43..7884c937 100644
--- a/packages/player/src/player/filters.ts
+++ b/packages/player/src/player/filters.ts
@@ -9,7 +9,7 @@ function stringToUint8Array(str: string) {
   return new Uint8Array(arr);
 }
 
-export function manipulateLicenseResponse(response: shaka.extern.Response) {
+export function manipulateLicenseResponse(response: shaka.extern.Response): void {
   // This is the wrapped license, which is a JSON string.
   const wrappedString = shaka.util.StringUtils.fromUTF8(response.data);
   // Parse the JSON string into an object
@@ -39,7 +39,7 @@ export function manipulateLicenseRequest(
     securityToken: string;
     streamingSessionId: string;
   },
-) {
+): void {
   if (
     request.body instanceof ArrayBuffer ||
     request.body instanceof Uint8Array
diff --git a/packages/player/src/player/index.ts b/packages/player/src/player/index.ts
index c73ffe7b..0d458624 100644
--- a/packages/player/src/player/index.ts
+++ b/packages/player/src/player/index.ts
@@ -32,11 +32,11 @@ const players = {
   shaka: undefined as ShakaPlayerType | undefined,
 };
 
-export function setPlayerConfig(allowedPlayers: Array<PlayerConfig>) {
+export function setPlayerConfig(allowedPlayers: Array<PlayerConfig>): void {
   playerConfig = allowedPlayers;
 }
 
-export async function resetAllPlayers() {
+export async function resetAllPlayers(): Promise<void> {
   await Promise.all(
     playerConfig.map(pc => {
       const player = players[pc.player];
@@ -53,7 +53,7 @@ export async function resetAllPlayers() {
   playerState.preloadPlayer = undefined;
 }
 
-export function setActivePlayer(player: Player) {
+export function setActivePlayer(player: Player): void {
   if (player.name !== 'nativePlayer' && players.native) {
     players.native.abandon();
   }
@@ -92,11 +92,11 @@ async function switchPlayerOnPlaybackEnd(_preloadPlayer: Player) {
  *
  * @see maybeSwitchPlayerOnEnd
  */
-export function cancelQueuedOnendedHandler() {
+export function cancelQueuedOnendedHandler(): void {
   events.removeEventListener('ended', endedHandler);
 }
 
-export function maybeSwitchPlayerOnEnd(preloadPlayer: Player) {
+export function maybeSwitchPlayerOnEnd(preloadPlayer: Player): void {
   if (
     playerState.activePlayer &&
     preloadPlayer.name === playerState.activePlayer.name
@@ -110,7 +110,7 @@ export function maybeSwitchPlayerOnEnd(preloadPlayer: Player) {
   events.addEventListener('ended', endedHandler, { once: true });
 }
 
-export async function getNativePlayer() {
+export async function getNativePlayer(): Promise<NativePlayerType> {
   const { default: NativePlayer } = await import('./nativePlayer');
 
   if (!players.native) {
@@ -120,7 +120,7 @@ export async function getNativePlayer() {
   return players.native;
 }
 
-async function getBrowserPlayer() {
+async function getBrowserPlayer(): Promise<BrowserPlayerType> {
   const { default: BrowserPlayer } = await import('./browserPlayer');
 
   if (!players.browser) {
@@ -143,7 +143,7 @@ async function getShakaPlayer() {
 export async function getAppropriatePlayer(
   productType: 'demo' | 'track' | 'video',
   audioQuality: AudioQuality | undefined,
-) {
+): Promise<BrowserPlayerType | NativePlayerType | ShakaPlayerType> {
   const appropriatePlayers = playerConfig
     .filter(pc => pc.itemTypes.includes(productType))
     .filter(pc =>
@@ -178,7 +178,7 @@ export async function getAppropriatePlayer(
 /**
  * Unload preloads in all booted players.
  */
-export async function unloadPreloadedMediaProduct() {
+export async function unloadPreloadedMediaProduct(): Promise<void> {
   await Promise.all(
     playerConfig.map(pc => {
       const player = players[pc.player];
diff --git a/packages/player/src/player/nativePlayer.ts b/packages/player/src/player/nativePlayer.ts
index 1f9cff04..6f943863 100644
--- a/packages/player/src/player/nativePlayer.ts
+++ b/packages/player/src/player/nativePlayer.ts
@@ -205,7 +205,7 @@ export default class NativePlayer extends BasePlayer {
   /**
    * Clean up native player before leaving for another player.
    */
-  abandon() {
+  abandon(): void {
     if (outputDevices && outputDevices.deviceMode === 'exclusive') {
       /*
         Remove lock on audio device so shaka can use it. Otherwise throws error later when shaka is
@@ -215,7 +215,7 @@ export default class NativePlayer extends BasePlayer {
     }
   }
 
-  getPosition() {
+  getPosition(): number {
     return this.currentTime;
   }
 
@@ -226,7 +226,7 @@ export default class NativePlayer extends BasePlayer {
    * I.e. wait for player to load it and emit mediaduration event, then we
    * can gather the duration data and send a media product transition.
    */
-  async handleAutomaticTransitionToPreloadedMediaProduct() {
+  async handleAutomaticTransitionToPreloadedMediaProduct(): Promise<void> {
     await this.nativeEvent('mediaduration');
 
     this.#preloadedLoadPayload = undefined;
@@ -273,7 +273,7 @@ export default class NativePlayer extends BasePlayer {
     this.mediaProductStarted(this.currentStreamingSessionId);
   }
 
-  async load(payload: LoadPayload, transition: 'explicit' | 'implicit') {
+  async load(payload: LoadPayload, transition: 'explicit' | 'implicit'): Promise<void> {
     this.debugLog('load', payload);
 
     this.currentTime = payload.assetPosition;
@@ -361,7 +361,7 @@ export default class NativePlayer extends BasePlayer {
     });
   }
 
-  async next(payload: LoadPayload) {
+  async next(payload: LoadPayload): Promise<void> {
     this.debugLog('next', payload);
 
     // Cancel previous preload to load a new one.
@@ -404,11 +404,11 @@ export default class NativePlayer extends BasePlayer {
     this.#preloadedLoadPayload = payload;
   }
 
-  pause() {
+  pause(): void {
     this.#player.pause();
   }
 
-  async play() {
+  async play(): Promise<void> {
     this.debugLog('play');
 
     await this.maybeHardReload();
@@ -429,7 +429,7 @@ export default class NativePlayer extends BasePlayer {
     this.#player.play();
   }
 
-  async playbackEngineEndedHandler(e: EndedEvent) {
+  async playbackEngineEndedHandler(e: EndedEvent): Promise<void> {
     if (this.isActivePlayer) {
       const { reason } = e.detail;
 
@@ -452,7 +452,7 @@ export default class NativePlayer extends BasePlayer {
     }
   }
 
-  registerEventListeners() {
+  registerEventListeners(): void {
     this.debugLog('registerEventListeners');
 
     this.#player.addEventListener('mediacurrenttime', (e: Event) => {
@@ -525,7 +525,7 @@ export default class NativePlayer extends BasePlayer {
 
   async reset(
     { keepPreload }: { keepPreload: boolean } = { keepPreload: false },
-  ) {
+  ): Promise<void> {
     if (this.currentStreamingSessionId === undefined) {
       return;
     }
@@ -554,7 +554,7 @@ export default class NativePlayer extends BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/no-misused-promises
-  async seek(seconds: number) {
+  async seek(seconds: number): Promise<void> {
     // Native player cannot seek until active state has happened.
     if (!this.hasStarted()) {
       await this.mediaStateChange('active');
@@ -569,7 +569,7 @@ export default class NativePlayer extends BasePlayer {
   }
 
   // Handles track "skip next" and progressions between shaka and native player
-  async skipToPreloadedMediaProduct() {
+  async skipToPreloadedMediaProduct(): Promise<void> {
     this.debugLog(
       'skipToPreloadedMediaProduct',
       this.preloadedStreamingSessionId,
@@ -608,7 +608,7 @@ export default class NativePlayer extends BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/require-await
-  async unloadPreloadedMediaProduct() {
+  async unloadPreloadedMediaProduct(): Promise<void> {
     this.debugLog(
       'unloadPreloadedMediaProduct',
       this.preloadedStreamingSessionId,
@@ -625,7 +625,7 @@ export default class NativePlayer extends BasePlayer {
     }
   }
 
-  updateDeviceMode() {
+  updateDeviceMode(): void {
     this.updateOutputDevice()?.catch(console.error);
 
     if (outputDevices) {
@@ -635,7 +635,7 @@ export default class NativePlayer extends BasePlayer {
     }
   }
 
-  updateOutputDevice() {
+  updateOutputDevice(): Promise<void> {
     if (!outputDevices) {
       return Promise.resolve();
     }
@@ -676,7 +676,7 @@ export default class NativePlayer extends BasePlayer {
     return Promise.resolve();
   }
 
-  get ready() {
+  get ready(): Promise<void> {
     return Promise.resolve();
   }
 
diff --git a/packages/player/src/player/shakaPlayer.ts b/packages/player/src/player/shakaPlayer.ts
index fee166af..4e88d113 100644
--- a/packages/player/src/player/shakaPlayer.ts
+++ b/packages/player/src/player/shakaPlayer.ts
@@ -829,11 +829,14 @@ export default class ShakaPlayer extends BasePlayer {
     );
   }
 
-  getPosition() {
+  getPosition(): number {
     return this.currentTime;
   }
 
-  async load(payload: LoadPayload, transition: 'explicit' | 'implicit') {
+  async load(
+    payload: LoadPayload,
+    transition: 'explicit' | 'implicit',
+  ): Promise<void> {
     this.debugLog('load', payload);
     await this.ready;
 
@@ -874,7 +877,7 @@ export default class ShakaPlayer extends BasePlayer {
     });
   }
 
-  async next(payload: LoadPayload) {
+  async next(payload: LoadPayload): Promise<void> {
     this.debugLog('next', payload);
 
     if (!this.shakaInstance) {
@@ -920,7 +923,7 @@ export default class ShakaPlayer extends BasePlayer {
     this.#isReset = false;
   }
 
-  pause() {
+  pause(): void {
     this.debugLog('pause');
 
     if (this.mediaElement) {
@@ -928,7 +931,7 @@ export default class ShakaPlayer extends BasePlayer {
     }
   }
 
-  async play() {
+  async play(): Promise<void> {
     this.debugLog('play');
 
     await this.maybeHardReload();
@@ -964,7 +967,7 @@ export default class ShakaPlayer extends BasePlayer {
     await this.mediaElement?.play();
   }
 
-  async playbackEngineEndedHandler(e: EndedEvent) {
+  async playbackEngineEndedHandler(e: EndedEvent): Promise<void> {
     if (this.isActivePlayer) {
       const { reason } = e.detail;
 
@@ -989,7 +992,7 @@ export default class ShakaPlayer extends BasePlayer {
 
   async reset(
     { keepPreload }: { keepPreload: boolean } = { keepPreload: false },
-  ) {
+  ): Promise<void> {
     this.debugLog('reset');
 
     if (this.#isReset) {
@@ -1026,13 +1029,13 @@ export default class ShakaPlayer extends BasePlayer {
   }
 
   // eslint-disable-next-line @typescript-eslint/no-misused-promises
-  seek(currentTime: number) {
+  seek(currentTime: number): Promise<number> {
     this.debugLog('seek', currentTime);
 
     const { mediaElement } = this;
 
     if (!mediaElement) {
-      return;
+      return Promise.resolve(0);
     }
 
     this.seekStart(this.currentTime);
@@ -1058,7 +1061,7 @@ export default class ShakaPlayer extends BasePlayer {
     });
   }
 
-  async skipToPreloadedMediaProduct() {
+  async skipToPreloadedMediaProduct(): Promise<void> {
     this.debugLog(
       'skipToPreloadedMediaProduct',
       this.preloadedStreamingSessionId,
@@ -1092,7 +1095,7 @@ export default class ShakaPlayer extends BasePlayer {
     return Promise.reject('Nothing preloaded.');
   }
 
-  togglePlayback() {
+  togglePlayback(): void {
     this.debugLog('togglePlayback');
     const { mediaElement } = this;
 
@@ -1105,7 +1108,7 @@ export default class ShakaPlayer extends BasePlayer {
     }
   }
 
-  async unloadPreloadedMediaProduct() {
+  async unloadPreloadedMediaProduct(): Promise<void> {
     this.debugLog(
       'unloadPreloadedMediaProduct',
       this.preloadedStreamingSessionId,
@@ -1120,7 +1123,7 @@ export default class ShakaPlayer extends BasePlayer {
     await this.#preloadManager?.destroy();
   }
 
-  async updateOutputDevice() {
+  async updateOutputDevice(): Promise<void> {
     if (!outputDevices) {
       return;
     }
@@ -1154,7 +1157,7 @@ export default class ShakaPlayer extends BasePlayer {
     return mediaElementOne;
   }
 
-  get ready() {
+  get ready(): Promise<void> {
     return this.#librariesLoad;
   }
 
diff --git a/packages/player/src/player/stalls.ts b/packages/player/src/player/stalls.ts
index 5f8d00d4..d8bf3db5 100644
--- a/packages/player/src/player/stalls.ts
+++ b/packages/player/src/player/stalls.ts
@@ -59,7 +59,7 @@ async function handlePlayingEvent(
     startTimestamp,
   };
 
-  StreamingMetrics.playbackStatistics({
+  StreamingMetrics.playbackStatisticsVideo({
     stalls: [stall],
     streamingSessionId,
   });
@@ -92,7 +92,7 @@ export function registerStalls(mediaEl: HTMLMediaElement) {
   mediaEl.addEventListener('playing', onPlaying);
   mediaEl.addEventListener('paused', onPaused);
 
-  return function unregister() {
+  return function unregister(): void {
     mediaEl.removeEventListener('seeking', onSeeking);
     mediaEl.removeEventListener('seeked', onSeeked);
     mediaEl.removeEventListener('playing', onPlaying);
diff --git a/packages/player/src/player/state.ts b/packages/player/src/player/state.ts
index 9a46c738..3e3f679c 100644
--- a/packages/player/src/player/state.ts
+++ b/packages/player/src/player/state.ts
@@ -1,3 +1,4 @@
+import type { MediaProduct } from '../api/interfaces';
 import { streamingSessionStore } from '../internal/helpers/streaming-session-store';
 
 import type BrowserPlayer from './browserPlayer';
@@ -10,7 +11,7 @@ class PlayerState {
   activePlayer: Player | undefined;
   preloadPlayer: Player | undefined;
 
-  get preloadedMediaProduct() {
+  get preloadedMediaProduct(): MediaProduct | undefined {
     return (
       streamingSessionStore.getMediaProductTransition(
         this.preloadedStreamingSessionId,
@@ -18,9 +19,9 @@ class PlayerState {
     );
   }
 
-  get preloadedStreamingSessionId() {
+  get preloadedStreamingSessionId(): string | undefined {
     return this.preloadPlayer?.preloadedStreamingSessionId ?? undefined;
   }
 }
 
-export const playerState = new PlayerState();
+export const playerState: PlayerState = new PlayerState();
diff --git a/packages/player/src/test-helpers.ts b/packages/player/src/test-helpers.ts
index e2409fe1..19671050 100644
--- a/packages/player/src/test-helpers.ts
+++ b/packages/player/src/test-helpers.ts
@@ -6,8 +6,9 @@ import { playerState } from './player/state';
 export { waitFor } from './internal/helpers/wait-for';
 
 import * as Player from './index';
+import type { CredentialsProvider } from '@tidal-music/common';
 
-export function getPreloadedStreamingSessionId() {
+export function getPreloadedStreamingSessionId(): string | undefined {
   return playerState.preloadedStreamingSessionId;
 }
 
@@ -45,9 +46,9 @@ await Auth.setCredentials({
 });
 
 Player.setCredentialsProvider(Auth.credentialsProvider);
-export const credentialsProvider = Auth.credentialsProvider;
+export const credentialsProvider: CredentialsProvider = Auth.credentialsProvider;
 
-export function waitForEvent(target: EventTarget, eventName: string) {
+export function waitForEvent(target: EventTarget, eventName: string): Promise<Event> {
   return new Promise(resolve => {
     target.addEventListener(eventName, event => resolve(event), false);
   });
@@ -89,7 +90,7 @@ class NativePlayerMock extends EventTarget {
   }
 }
 
-export function mockNativePlayer() {
+export function mockNativePlayer(): void {
   // eslint-disable-next-line @typescript-eslint/ban-ts-comment
   // @ts-ignore
   window.NativePlayerComponent = {
diff --git a/packages/player/tsconfig.json b/packages/player/tsconfig.json
index ef0a939b..3fcb7a8b 100644
--- a/packages/player/tsconfig.json
+++ b/packages/player/tsconfig.json
@@ -12,7 +12,9 @@
     "types": [
       "mocha"
     ],
-    "sourceMap": false
+    "sourceMap": false,
+    "declaration": true,
+    "isolatedDeclarations": true,
   },
   "include": [
     "."
diff --git a/packages/player/vite-legacy.config.ts b/packages/player/vite-legacy.config.ts
index f8e07a69..da2bb46d 100644
--- a/packages/player/vite-legacy.config.ts
+++ b/packages/player/vite-legacy.config.ts
@@ -1,10 +1,10 @@
 import version from 'vite-plugin-package-version';
 import topLevelAwait from 'vite-plugin-top-level-await';
-import { defineConfig, mergeConfig } from 'vitest/config';
+import { defineConfig, mergeConfig, type UserConfig } from 'vitest/config';
 
 import defaultViteConfig from './vite.config';
 
-export default mergeConfig(
+const config: UserConfig = mergeConfig(
   defaultViteConfig,
   defineConfig({
     build: {
@@ -19,3 +19,5 @@ export default mergeConfig(
     plugins: [version(), topLevelAwait()],
   }),
 );
+
+export default config;
diff --git a/packages/player/vite.config.ts b/packages/player/vite.config.ts
index 22f1f7a6..e8b5248f 100644
--- a/packages/player/vite.config.ts
+++ b/packages/player/vite.config.ts
@@ -1,8 +1,8 @@
 import dts from 'vite-plugin-dts';
 import version from 'vite-plugin-package-version';
-import { defineConfig } from 'vitest/config';
+import { type UserConfig, defineConfig } from 'vitest/config';
 
-export default defineConfig({
+const config: UserConfig = defineConfig({
   build: {
     lib: {
       entry: 'src/index.ts',
@@ -27,3 +27,5 @@ export default defineConfig({
     unstubGlobals: true,
   },
 });
+
+export default config;
diff --git a/packages/true-time/src/index.ts b/packages/true-time/src/index.ts
index ddfd9d0e..745a0959 100644
--- a/packages/true-time/src/index.ts
+++ b/packages/true-time/src/index.ts
@@ -19,7 +19,7 @@ export class TrueTime {
    * @returns The current adjusted time (or the client time if not synced yet).
    */
   // eslint-disable-next-line no-restricted-syntax
-  now(clientCurrentTime = Date.now()): number {
+  now(clientCurrentTime: number = Date.now()): number {
     if (!this.#serverTime || !this.#clientStartTime) {
       console.warn('TrueTime is not yet synchronized');
       return clientCurrentTime;
@@ -91,4 +91,4 @@ export class TrueTime {
   }
 }
 
-export const trueTime = new TrueTime('https://api.tidal.com/v1/ping');
+export const trueTime: TrueTime = new TrueTime('https://api.tidal.com/v1/ping');
diff --git a/packages/true-time/tsconfig.json b/packages/true-time/tsconfig.json
index a8ed344e..bbbb6299 100644
--- a/packages/true-time/tsconfig.json
+++ b/packages/true-time/tsconfig.json
@@ -1,7 +1,9 @@
 {
   "extends": "../../tsconfig.json",
   "compilerOptions": {
-    "baseUrl": "."
+    "baseUrl": ".",
+    "declaration": true,
+    "isolatedDeclarations": true,
   },
   "include": ["."]
 }
diff --git a/packages/true-time/vite.config.ts b/packages/true-time/vite.config.ts
index 5e08bd4e..25efaced 100644
--- a/packages/true-time/vite.config.ts
+++ b/packages/true-time/vite.config.ts
@@ -1,7 +1,7 @@
 import dts from 'vite-plugin-dts';
-import { defineConfig } from 'vitest/config';
+import { defineConfig, type UserConfig } from 'vitest/config';
 
-export default defineConfig({
+const config: UserConfig = defineConfig({
   build: {
     lib: {
       entry: 'src/index.ts',
@@ -26,3 +26,5 @@ export default defineConfig({
     unstubGlobals: true,
   },
 });
+
+export default config;