diff --git a/CHANGELOG.md b/CHANGELOG.md
index e4cc3c1266..0bb31b2e6e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 
 * `RtpStreamSend`: Reset RTP retransmission buffer upon RTP sequence number reset ([PR #1041](https://github.com/versatica/mediasoup/pull/1041)).
 * `RtpRetransmissionBuffer`: Handle corner case in which received packet has lower seq than newest packet in the buffer but higher timestamp  ([PR #1044](https://github.com/versatica/mediasoup/pull/1044)).
+* Node: Make `appData` TS typed and writable ([PR #1046](https://github.com/versatica/mediasoup/pull/1046), credits to @mango-martin).
 
 
 ### 3.11.19
diff --git a/node/.eslintrc.js b/node/.eslintrc.js
index f681e15d1c..ca8e7cefc4 100644
--- a/node/.eslintrc.js
+++ b/node/.eslintrc.js
@@ -75,10 +75,10 @@ const eslintConfig =
 				beforeLineComment  : false
 			}
 		],
-		'max-len' : [ 2, 90,
+		'max-len' : [ 2, 100,
 			{
 				tabWidth               : 2,
-				comments               : 90,
+				comments               : 84,
 				ignoreUrls             : true,
 				ignoreStrings          : true,
 				ignoreTemplateLiterals : true,
diff --git a/node/src/ActiveSpeakerObserver.ts b/node/src/ActiveSpeakerObserver.ts
index f5ebd29337..a9af22c569 100644
--- a/node/src/ActiveSpeakerObserver.ts
+++ b/node/src/ActiveSpeakerObserver.ts
@@ -7,15 +7,16 @@ import {
 	RtpObserverConstructorOptions
 } from './RtpObserver';
 import { Producer } from './Producer';
+import { AppData } from './types';
 
-export type ActiveSpeakerObserverOptions =
+export type ActiveSpeakerObserverOptions<ActiveSpeakerObserverAppData extends AppData = AppData> =
 {
 	interval?: number;
 
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: ActiveSpeakerObserverAppData;
 };
 
 export type ActiveSpeakerObserverDominantSpeaker =
@@ -36,16 +37,18 @@ export type ActiveSpeakerObserverObserverEvents = RtpObserverObserverEvents &
 	dominantspeaker: [ActiveSpeakerObserverDominantSpeaker];
 };
 
-type RtpObserverObserverConstructorOptions = RtpObserverConstructorOptions;
+type RtpObserverObserverConstructorOptions<ActiveSpeakerObserverAppData> =
+	RtpObserverConstructorOptions<ActiveSpeakerObserverAppData>;
 
 const logger = new Logger('ActiveSpeakerObserver');
 
-export class ActiveSpeakerObserver extends RtpObserver<ActiveSpeakerObserverEvents>
+export class ActiveSpeakerObserver<ActiveSpeakerObserverAppData extends AppData = AppData>
+	extends RtpObserver<ActiveSpeakerObserverEvents, ActiveSpeakerObserverAppData>
 {
 	/**
 	 * @private
 	 */
-	constructor(options: RtpObserverObserverConstructorOptions)
+	constructor(options: RtpObserverObserverConstructorOptions<ActiveSpeakerObserverAppData>)
 	{
 		super(options);
 
diff --git a/node/src/AudioLevelObserver.ts b/node/src/AudioLevelObserver.ts
index 0b0f8cf6c3..597e3ed882 100644
--- a/node/src/AudioLevelObserver.ts
+++ b/node/src/AudioLevelObserver.ts
@@ -7,8 +7,9 @@ import {
 	RtpObserverConstructorOptions
 } from './RtpObserver';
 import { Producer } from './Producer';
+import { AppData } from './types';
 
-export type AudioLevelObserverOptions =
+export type AudioLevelObserverOptions<AudioLevelObserverAppData extends AppData = AppData> =
 {
 	/**
 	 * Maximum number of entries in the 'volumes”' event. Default 1.
@@ -29,7 +30,7 @@ export type AudioLevelObserverOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: AudioLevelObserverAppData;
 };
 
 export type AudioLevelObserverVolume =
@@ -58,16 +59,18 @@ export type AudioLevelObserverObserverEvents = RtpObserverObserverEvents &
 	silence: [];
 };
 
-type AudioLevelObserverConstructorOptions = RtpObserverConstructorOptions;
+type AudioLevelObserverConstructorOptions<AudioLevelObserverAppData> =
+	RtpObserverConstructorOptions<AudioLevelObserverAppData>;
 
 const logger = new Logger('AudioLevelObserver');
 
-export class AudioLevelObserver extends RtpObserver<AudioLevelObserverEvents>
+export class AudioLevelObserver<AudioLevelObserverAppData extends AppData = AppData>
+	extends RtpObserver<AudioLevelObserverEvents, AudioLevelObserverAppData>
 {
 	/**
 	 * @private
 	 */
-	constructor(options: AudioLevelObserverConstructorOptions)
+	constructor(options: AudioLevelObserverConstructorOptions<AudioLevelObserverAppData>)
 	{
 		super(options);
 
diff --git a/node/src/Consumer.ts b/node/src/Consumer.ts
index 5bf3c6d5cb..bcf09e3c20 100644
--- a/node/src/Consumer.ts
+++ b/node/src/Consumer.ts
@@ -9,8 +9,9 @@ import {
 	RtpCapabilities,
 	RtpParameters
 } from './RtpParameters';
+import { AppData } from './types';
 
-export type ConsumerOptions =
+export type ConsumerOptions<ConsumerAppData extends AppData = AppData> =
 {
 	/**
 	 * The id of the Producer to consume.
@@ -75,7 +76,7 @@ export type ConsumerOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: ConsumerAppData;
 };
 
 /**
@@ -211,7 +212,8 @@ type ConsumerData =
 
 const logger = new Logger('Consumer');
 
-export class Consumer extends EnhancedEventEmitter<ConsumerEvents>
+export class Consumer<ConsumerAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<ConsumerEvents>
 {
 	// Internal data.
 	readonly #internal: ConsumerInternal;
@@ -229,7 +231,7 @@ export class Consumer extends EnhancedEventEmitter<ConsumerEvents>
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: ConsumerAppData;
 
 	// Paused flag.
 	#paused = false;
@@ -272,7 +274,7 @@ export class Consumer extends EnhancedEventEmitter<ConsumerEvents>
 			data: ConsumerData;
 			channel: Channel;
 			payloadChannel: PayloadChannel;
-			appData?: Record<string, unknown>;
+			appData?: ConsumerAppData;
 			paused: boolean;
 			producerPaused: boolean;
 			score?: ConsumerScore;
@@ -287,7 +289,7 @@ export class Consumer extends EnhancedEventEmitter<ConsumerEvents>
 		this.#data = data;
 		this.#channel = channel;
 		this.#payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as ConsumerAppData;
 		this.#paused = paused;
 		this.#producerPaused = producerPaused;
 		this.#score = score;
@@ -395,17 +397,17 @@ export class Consumer extends EnhancedEventEmitter<ConsumerEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): ConsumerAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: ConsumerAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
diff --git a/node/src/DataConsumer.ts b/node/src/DataConsumer.ts
index 79f1742a56..a85413c38f 100644
--- a/node/src/DataConsumer.ts
+++ b/node/src/DataConsumer.ts
@@ -4,8 +4,9 @@ import { Channel } from './Channel';
 import { PayloadChannel } from './PayloadChannel';
 import { TransportInternal } from './Transport';
 import { SctpStreamParameters } from './SctpParameters';
+import { AppData } from './types';
 
-export type DataConsumerOptions =
+export type DataConsumerOptions<DataConsumerAppData extends AppData = AppData> =
 {
 	/**
 	 * The id of the DataProducer to consume.
@@ -39,7 +40,7 @@ export type DataConsumerOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: DataConsumerAppData;
 };
 
 export type DataConsumerStat =
@@ -91,7 +92,8 @@ type DataConsumerData =
 
 const logger = new Logger('DataConsumer');
 
-export class DataConsumer extends EnhancedEventEmitter<DataConsumerEvents>
+export class DataConsumer<DataConsumerAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<DataConsumerEvents>
 {
 	// Internal data.
 	readonly #internal: DataConsumerInternal;
@@ -109,7 +111,7 @@ export class DataConsumer extends EnhancedEventEmitter<DataConsumerEvents>
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: DataConsumerAppData;
 
 	// Observer instance.
 	readonly #observer = new EnhancedEventEmitter<DataConsumerObserverEvents>();
@@ -130,7 +132,7 @@ export class DataConsumer extends EnhancedEventEmitter<DataConsumerEvents>
 			data: DataConsumerData;
 			channel: Channel;
 			payloadChannel: PayloadChannel;
-			appData?: Record<string, unknown>;
+			appData?: DataConsumerAppData;
 		}
 	)
 	{
@@ -142,7 +144,7 @@ export class DataConsumer extends EnhancedEventEmitter<DataConsumerEvents>
 		this.#data = data;
 		this.#channel = channel;
 		this.#payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as DataConsumerAppData;
 
 		this.handleWorkerNotifications();
 	}
@@ -206,17 +208,17 @@ export class DataConsumer extends EnhancedEventEmitter<DataConsumerEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): DataConsumerAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: DataConsumerAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
diff --git a/node/src/DataProducer.ts b/node/src/DataProducer.ts
index 7d48eb8eb9..94320ab26d 100644
--- a/node/src/DataProducer.ts
+++ b/node/src/DataProducer.ts
@@ -4,8 +4,9 @@ import { Channel } from './Channel';
 import { PayloadChannel } from './PayloadChannel';
 import { TransportInternal } from './Transport';
 import { SctpStreamParameters } from './SctpParameters';
+import { AppData } from './types';
 
-export type DataProducerOptions =
+export type DataProducerOptions<DataProducerAppData extends AppData = AppData> =
 {
 	/**
 	 * DataProducer id (just for Router.pipeToRouter() method).
@@ -31,7 +32,7 @@ export type DataProducerOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: DataProducerAppData;
 };
 
 export type DataProducerStat =
@@ -76,7 +77,8 @@ type DataProducerData =
 
 const logger = new Logger('DataProducer');
 
-export class DataProducer extends EnhancedEventEmitter<DataProducerEvents>
+export class DataProducer<DataProducerAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<DataProducerEvents>
 {
 	// Internal data.
 	readonly #internal: DataProducerInternal;
@@ -94,7 +96,7 @@ export class DataProducer extends EnhancedEventEmitter<DataProducerEvents>
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: DataProducerAppData;
 
 	// Observer instance.
 	readonly #observer = new EnhancedEventEmitter<DataProducerObserverEvents>();
@@ -115,7 +117,7 @@ export class DataProducer extends EnhancedEventEmitter<DataProducerEvents>
 			data: DataProducerData;
 			channel: Channel;
 			payloadChannel: PayloadChannel;
-			appData?: Record<string, unknown>;
+			appData?: DataProducerAppData;
 		}
 	)
 	{
@@ -127,7 +129,7 @@ export class DataProducer extends EnhancedEventEmitter<DataProducerEvents>
 		this.#data = data;
 		this.#channel = channel;
 		this.#payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as DataProducerAppData;
 
 		this.handleWorkerNotifications();
 	}
@@ -183,17 +185,17 @@ export class DataProducer extends EnhancedEventEmitter<DataProducerEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): DataProducerAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: DataProducerAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
diff --git a/node/src/DirectTransport.ts b/node/src/DirectTransport.ts
index 4a6fc7bea7..f4bc0be37a 100644
--- a/node/src/DirectTransport.ts
+++ b/node/src/DirectTransport.ts
@@ -8,8 +8,9 @@ import {
 	TransportConstructorOptions
 } from './Transport';
 import { SctpParameters } from './SctpParameters';
+import { AppData } from './types';
 
-export type DirectTransportOptions =
+export type DirectTransportOptions<DirectTransportAppData extends AppData = AppData> =
 {
 	/**
 	 * Maximum allowed size for direct messages sent from DataProducers.
@@ -20,7 +21,7 @@ export type DirectTransportOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: DirectTransportAppData;
 };
 
 export type DirectTransportStat =
@@ -58,10 +59,11 @@ export type DirectTransportObserverEvents = TransportObserverEvents &
 	rtcp: [Buffer];
 };
 
-type DirectTransportConstructorOptions = TransportConstructorOptions &
-{
-	data: DirectTransportData;
-};
+type DirectTransportConstructorOptions<DirectTransportAppData> =
+	TransportConstructorOptions<DirectTransportAppData> &
+	{
+		data: DirectTransportData;
+	};
 
 export type DirectTransportData =
 {
@@ -70,8 +72,8 @@ export type DirectTransportData =
 
 const logger = new Logger('DirectTransport');
 
-export class DirectTransport extends
-	Transport<DirectTransportEvents, DirectTransportObserverEvents>
+export class DirectTransport<DirectTransportAppData extends AppData = AppData>
+	extends Transport<DirectTransportEvents, DirectTransportObserverEvents, DirectTransportAppData>
 {
 	// DirectTransport data.
 	readonly #data: DirectTransportData;
@@ -79,7 +81,7 @@ export class DirectTransport extends
 	/**
 	 * @private
 	 */
-	constructor(options: DirectTransportConstructorOptions)
+	constructor(options: DirectTransportConstructorOptions<DirectTransportAppData>)
 	{
 		super(options);
 
diff --git a/node/src/PipeTransport.ts b/node/src/PipeTransport.ts
index 3aced3c836..f312a79ec6 100644
--- a/node/src/PipeTransport.ts
+++ b/node/src/PipeTransport.ts
@@ -14,8 +14,9 @@ import {
 import { Consumer, ConsumerType } from './Consumer';
 import { SctpParameters, NumSctpStreams } from './SctpParameters';
 import { SrtpParameters } from './SrtpParameters';
+import { AppData } from './types';
 
-export type PipeTransportOptions =
+export type PipeTransportOptions<PipeTransportAppData extends AppData = AppData> =
 {
 	/**
 	 * Listening IP address.
@@ -67,7 +68,7 @@ export type PipeTransportOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: PipeTransportAppData;
 };
 
 export type PipeTransportStat =
@@ -98,7 +99,7 @@ export type PipeTransportStat =
 	tuple: TransportTuple;
 };
 
-export type PipeConsumerOptions =
+export type PipeConsumerOptions<ConsumerAppData> =
 {
 	/**
 	 * The id of the Producer to consume.
@@ -108,7 +109,7 @@ export type PipeConsumerOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: ConsumerAppData;
 };
 
 export type PipeTransportEvents = TransportEvents &
@@ -121,10 +122,11 @@ export type PipeTransportObserverEvents = TransportObserverEvents &
 	sctpstatechange: [SctpState];
 };
 
-type PipeTransportConstructorOptions = TransportConstructorOptions &
-{
-	data: PipeTransportData;
-};
+type PipeTransportConstructorOptions<PipeTransportAppData> =
+	TransportConstructorOptions<PipeTransportAppData> &
+	{
+		data: PipeTransportData;
+	};
 
 export type PipeTransportData =
 {
@@ -137,8 +139,8 @@ export type PipeTransportData =
 
 const logger = new Logger('PipeTransport');
 
-export class PipeTransport
-	extends Transport<PipeTransportEvents, PipeTransportObserverEvents>
+export class PipeTransport<PipeTransportAppData extends AppData = AppData>
+	extends Transport<PipeTransportEvents, PipeTransportObserverEvents, PipeTransportAppData>
 {
 	// PipeTransport data.
 	readonly #data: PipeTransportData;
@@ -146,7 +148,7 @@ export class PipeTransport
 	/**
 	 * @private
 	 */
-	constructor(options: PipeTransportConstructorOptions)
+	constructor(options: PipeTransportConstructorOptions<PipeTransportAppData>)
 	{
 		super(options);
 
@@ -285,7 +287,12 @@ export class PipeTransport
 	 *
 	 * @override
 	 */
-	async consume({ producerId, appData }: PipeConsumerOptions): Promise<Consumer>
+	async consume<ConsumerAppData extends AppData = AppData>(
+		{
+			producerId,
+			appData
+		}: PipeConsumerOptions<ConsumerAppData>
+	): Promise<Consumer<ConsumerAppData>>
 	{
 		logger.debug('consume()');
 
@@ -334,7 +341,7 @@ export class PipeTransport
 			type : 'pipe' as ConsumerType
 		};
 
-		const consumer = new Consumer(
+		const consumer = new Consumer<ConsumerAppData>(
 			{
 				internal :
 				{
diff --git a/node/src/PlainTransport.ts b/node/src/PlainTransport.ts
index 256d504950..23c4e266c0 100644
--- a/node/src/PlainTransport.ts
+++ b/node/src/PlainTransport.ts
@@ -11,8 +11,9 @@ import {
 } from './Transport';
 import { SctpParameters, NumSctpStreams } from './SctpParameters';
 import { SrtpParameters, SrtpCryptoSuite } from './SrtpParameters';
+import { AppData } from './types';
 
-export type PlainTransportOptions =
+export type PlainTransportOptions<PlainTransportAppData extends AppData = AppData> =
 {
 	/**
 	 * Listening IP address.
@@ -75,7 +76,7 @@ export type PlainTransportOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: PlainTransportAppData;
 };
 
 export type PlainTransportStat =
@@ -123,10 +124,11 @@ export type PlainTransportObserverEvents = TransportObserverEvents &
 	sctpstatechange: [SctpState];	
 };
 
-type PlainTransportConstructorOptions = TransportConstructorOptions &
-{
-	data: PlainTransportData;
-};
+type PlainTransportConstructorOptions<PlainTransportAppData> =
+	TransportConstructorOptions<PlainTransportAppData> &
+	{
+		data: PlainTransportData;
+	};
 
 export type PlainTransportData =
 {
@@ -141,8 +143,8 @@ export type PlainTransportData =
 
 const logger = new Logger('PlainTransport');
 
-export class PlainTransport extends
-	Transport<PlainTransportEvents, PlainTransportObserverEvents>
+export class PlainTransport<PlainTransportAppData extends AppData = AppData>
+	extends Transport<PlainTransportEvents, PlainTransportObserverEvents, PlainTransportAppData>
 {
 	// PlainTransport data.
 	readonly #data: PlainTransportData;
@@ -150,7 +152,7 @@ export class PlainTransport extends
 	/**
 	 * @private
 	 */
-	constructor(options: PlainTransportConstructorOptions)
+	constructor(options: PlainTransportConstructorOptions<PlainTransportAppData>)
 	{
 		super(options);
 
diff --git a/node/src/Producer.ts b/node/src/Producer.ts
index 0046b6f672..2d152ffb40 100644
--- a/node/src/Producer.ts
+++ b/node/src/Producer.ts
@@ -4,8 +4,9 @@ import { Channel } from './Channel';
 import { PayloadChannel } from './PayloadChannel';
 import { TransportInternal } from './Transport';
 import { MediaKind, RtpParameters } from './RtpParameters';
+import { AppData } from './types';
 
-export type ProducerOptions =
+export type ProducerOptions<ProducerAppData extends AppData = AppData> =
 {
 	/**
 	 * Producer id (just for Router.pipeToRouter() method).
@@ -36,7 +37,7 @@ export type ProducerOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: ProducerAppData;
 };
 
 /**
@@ -176,7 +177,8 @@ type ProducerData =
 
 const logger = new Logger('Producer');
 
-export class Producer extends EnhancedEventEmitter<ProducerEvents>
+export class Producer<ProducerAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<ProducerEvents>
 {
 	// Internal data.
 	readonly #internal: ProducerInternal;
@@ -194,7 +196,7 @@ export class Producer extends EnhancedEventEmitter<ProducerEvents>
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: ProducerAppData;
 
 	// Paused flag.
 	#paused = false;
@@ -222,7 +224,7 @@ export class Producer extends EnhancedEventEmitter<ProducerEvents>
 			data: ProducerData;
 			channel: Channel;
 			payloadChannel: PayloadChannel;
-			appData?: Record<string, unknown>;
+			appData?: ProducerAppData;
 			paused: boolean;
 		}
 	)
@@ -235,7 +237,7 @@ export class Producer extends EnhancedEventEmitter<ProducerEvents>
 		this.#data = data;
 		this.#channel = channel;
 		this.#payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as ProducerAppData;
 		this.#paused = paused;
 
 		this.handleWorkerNotifications();
@@ -310,17 +312,17 @@ export class Producer extends EnhancedEventEmitter<ProducerEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): ProducerAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: ProducerAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
diff --git a/node/src/Router.ts b/node/src/Router.ts
index 51a2e876da..21466d4c23 100644
--- a/node/src/Router.ts
+++ b/node/src/Router.ts
@@ -19,8 +19,9 @@ import { ActiveSpeakerObserver, ActiveSpeakerObserverOptions } from './ActiveSpe
 import { AudioLevelObserver, AudioLevelObserverOptions } from './AudioLevelObserver';
 import { RtpCapabilities, RtpCodecCapability } from './RtpParameters';
 import { NumSctpStreams } from './SctpParameters';
+import { AppData } from './types';
 
-export type RouterOptions =
+export type RouterOptions<RouterAppData extends AppData = AppData> =
 {
 	/**
 	 * Router media codecs.
@@ -30,7 +31,7 @@ export type RouterOptions =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: RouterAppData;
 };
 
 export type PipeToRouterOptions =
@@ -130,7 +131,8 @@ type RouterData =
 
 const logger = new Logger('Router');
 
-export class Router extends EnhancedEventEmitter<RouterEvents>
+export class Router<RouterAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<RouterEvents>
 {
 	// Internal data.
 	readonly #internal: RouterInternal;
@@ -148,7 +150,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: RouterAppData;
 
 	// Transports map.
 	readonly #transports: Map<string, Transport> = new Map();
@@ -186,7 +188,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 			data: RouterData;
 			channel: Channel;
 			payloadChannel: PayloadChannel;
-			appData?: Record<string, unknown>;
+			appData?: RouterAppData;
 		}
 	)
 	{
@@ -198,7 +200,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 		this.#data = data;
 		this.#channel = channel;
 		this.#payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as RouterAppData;
 	}
 
 	/**
@@ -228,17 +230,17 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): RouterAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: RouterAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
@@ -358,7 +360,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * Create a WebRtcTransport.
 	 */
-	async createWebRtcTransport(
+	async createWebRtcTransport<WebRtcTransportAppData extends AppData = AppData>(
 		{
 			webRtcServer,
 			listenIps,
@@ -373,8 +375,8 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 			maxSctpMessageSize = 262144,
 			sctpSendBufferSize = 262144,
 			appData
-		}: WebRtcTransportOptions
-	): Promise<WebRtcTransport>
+		}: WebRtcTransportOptions<WebRtcTransportAppData>
+	): Promise<WebRtcTransport<WebRtcTransportAppData>>
 	{
 		logger.debug('createWebRtcTransport()');
 
@@ -431,7 +433,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 			? await this.#channel.request('router.createWebRtcTransportWithServer', this.#internal.routerId, reqData)
 			: await this.#channel.request('router.createWebRtcTransport', this.#internal.routerId, reqData);
 
-		const transport = new WebRtcTransport(
+		const transport = new WebRtcTransport<WebRtcTransportAppData>(
 			{
 				internal :
 				{
@@ -477,7 +479,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * Create a PlainTransport.
 	 */
-	async createPlainTransport(
+	async createPlainTransport<PlainTransportAppData extends AppData = AppData>(
 		{
 			listenIp,
 			port,
@@ -490,8 +492,8 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 			enableSrtp = false,
 			srtpCryptoSuite = 'AES_CM_128_HMAC_SHA1_80',
 			appData
-		}: PlainTransportOptions
-	): Promise<PlainTransport>
+		}: PlainTransportOptions<PlainTransportAppData>
+	): Promise<PlainTransport<PlainTransportAppData>>
 	{
 		logger.debug('createPlainTransport()');
 
@@ -540,7 +542,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 		const data =
 			await this.#channel.request('router.createPlainTransport', this.#internal.routerId, reqData);
 
-		const transport = new PlainTransport(
+		const transport = new PlainTransport<PlainTransportAppData>(
 			{
 				internal :
 				{
@@ -581,7 +583,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * Create a PipeTransport.
 	 */
-	async createPipeTransport(
+	async createPipeTransport<PipeTransportAppData extends AppData = AppData>(
 		{
 			listenIp,
 			port,
@@ -592,8 +594,8 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 			enableRtx = false,
 			enableSrtp = false,
 			appData
-		}: PipeTransportOptions
-	): Promise<PipeTransport>
+		}: PipeTransportOptions<PipeTransportAppData>
+	): Promise<PipeTransport<PipeTransportAppData>>
 	{
 		logger.debug('createPipeTransport()');
 
@@ -640,7 +642,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 		const data =
 			await this.#channel.request('router.createPipeTransport', this.#internal.routerId, reqData);
 
-		const transport = new PipeTransport(
+		const transport = new PipeTransport<PipeTransportAppData>(
 			{
 				internal :
 				{
@@ -681,15 +683,15 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * Create a DirectTransport.
 	 */
-	async createDirectTransport(
+	async createDirectTransport<DirectTransportAppData extends AppData = AppData>(
 		{
 			maxMessageSize = 262144,
 			appData
-		}: DirectTransportOptions =
+		}: DirectTransportOptions<DirectTransportAppData> =
 		{
 			maxMessageSize : 262144
 		}
-	): Promise<DirectTransport>
+	): Promise<DirectTransport<DirectTransportAppData>>
 	{
 		logger.debug('createDirectTransport()');
 
@@ -703,7 +705,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 		const data =
 			await this.#channel.request('router.createDirectTransport', this.#internal.routerId, reqData);
 
-		const transport = new DirectTransport(
+		const transport = new DirectTransport<DirectTransportAppData>(
 			{
 				internal :
 				{
@@ -1065,12 +1067,12 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * Create an ActiveSpeakerObserver
 	 */
-	async createActiveSpeakerObserver(
+	async createActiveSpeakerObserver<ActiveSpeakerObserverAppData extends AppData = AppData>(
 		{
 			interval = 300,
 			appData
-		}: ActiveSpeakerObserverOptions = {}
-	): Promise<ActiveSpeakerObserver>
+		}: ActiveSpeakerObserverOptions<ActiveSpeakerObserverAppData> = {}
+	): Promise<ActiveSpeakerObserver<ActiveSpeakerObserverAppData>>
 	{
 		logger.debug('createActiveSpeakerObserver()');
 
@@ -1087,7 +1089,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 
 		await this.#channel.request('router.createActiveSpeakerObserver', this.#internal.routerId, reqData);
 
-		const activeSpeakerObserver = new ActiveSpeakerObserver(
+		const activeSpeakerObserver = new ActiveSpeakerObserver<ActiveSpeakerObserverAppData>(
 			{
 				internal :
 				{
@@ -1117,14 +1119,14 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 	/**
 	 * Create an AudioLevelObserver.
 	 */
-	async createAudioLevelObserver(
+	async createAudioLevelObserver<AudioLevelObserverAppData extends AppData = AppData>(
 		{
 			maxEntries = 1,
 			threshold = -80,
 			interval = 1000,
 			appData
-		}: AudioLevelObserverOptions = {}
-	): Promise<AudioLevelObserver>
+		}: AudioLevelObserverOptions<AudioLevelObserverAppData> = {}
+	): Promise<AudioLevelObserver<AudioLevelObserverAppData>>
 	{
 		logger.debug('createAudioLevelObserver()');
 
@@ -1143,7 +1145,7 @@ export class Router extends EnhancedEventEmitter<RouterEvents>
 
 		await this.#channel.request('router.createAudioLevelObserver', this.#internal.routerId, reqData);
 
-		const audioLevelObserver = new AudioLevelObserver(
+		const audioLevelObserver = new AudioLevelObserver<AudioLevelObserverAppData>(
 			{
 				internal :
 				{
diff --git a/node/src/RtpObserver.ts b/node/src/RtpObserver.ts
index 324fc3313f..3821d728d4 100644
--- a/node/src/RtpObserver.ts
+++ b/node/src/RtpObserver.ts
@@ -4,6 +4,7 @@ import { Channel } from './Channel';
 import { PayloadChannel } from './PayloadChannel';
 import { RouterInternal } from './Router';
 import { Producer } from './Producer';
+import { AppData } from './types';
 
 export type RtpObserverEvents =
 {
@@ -21,12 +22,12 @@ export type RtpObserverObserverEvents =
 	removeproducer: [Producer];
 };
 
-export type RtpObserverConstructorOptions =
+export type RtpObserverConstructorOptions<RtpObserverAppData> =
 {
 	internal: RtpObserverObserverInternal;
 	channel: Channel;
 	payloadChannel: PayloadChannel;
-	appData?: Record<string, unknown>;
+	appData?: RtpObserverAppData;
 	getProducerById: (producerId: string) => Producer | undefined;
 };
 
@@ -45,8 +46,10 @@ export type RtpObserverAddRemoveProducerOptions =
 	producerId: string;
 };
 
-export class RtpObserver<E extends RtpObserverEvents = RtpObserverEvents>
-	extends EnhancedEventEmitter<E>
+export class RtpObserver
+	<Events extends RtpObserverEvents = RtpObserverEvents,
+	RtpObserverAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<Events>
 {
 	// Internal data.
 	protected readonly internal: RtpObserverObserverInternal;
@@ -64,7 +67,7 @@ export class RtpObserver<E extends RtpObserverEvents = RtpObserverEvents>
 	#paused = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: RtpObserverAppData;
 
 	// Method to retrieve a Producer.
 	protected readonly getProducerById: (producerId: string) => Producer | undefined;
@@ -83,7 +86,7 @@ export class RtpObserver<E extends RtpObserverEvents = RtpObserverEvents>
 			payloadChannel,
 			appData,
 			getProducerById
-		}: RtpObserverConstructorOptions
+		}: RtpObserverConstructorOptions<RtpObserverAppData>
 	)
 	{
 		super();
@@ -93,7 +96,7 @@ export class RtpObserver<E extends RtpObserverEvents = RtpObserverEvents>
 		this.internal = internal;
 		this.channel = channel;
 		this.payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as RtpObserverAppData;
 		this.getProducerById = getProducerById;
 	}
 
@@ -124,17 +127,17 @@ export class RtpObserver<E extends RtpObserverEvents = RtpObserverEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): RtpObserverAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: RtpObserverAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
diff --git a/node/src/Transport.ts b/node/src/Transport.ts
index 5463b547a6..5d31e794ac 100644
--- a/node/src/Transport.ts
+++ b/node/src/Transport.ts
@@ -24,6 +24,7 @@ import {
 } from './DataConsumer';
 import { RtpCapabilities } from './RtpParameters';
 import { SctpStreamParameters } from './SctpParameters';
+import { AppData } from './types';
 
 export type TransportListenIp =
 {
@@ -110,13 +111,13 @@ export type TransportObserverEvents =
 	trace: [TransportTraceEventData];
 };
 
-export type TransportConstructorOptions =
+export type TransportConstructorOptions<TransportAppData> =
 {
 	internal: TransportInternal;
 	data: TransportData;
 	channel: Channel;
 	payloadChannel: PayloadChannel;
-	appData?: Record<string, unknown>;
+	appData?: TransportAppData;
 	getRouterRtpCapabilities: () => RtpCapabilities;
 	getProducerById: (producerId: string) => Producer | undefined;
 	getDataProducerById: (dataProducerId: string) => DataProducer | undefined;
@@ -135,8 +136,10 @@ type TransportData =
 
 const logger = new Logger('Transport');
 
-export class Transport<Events extends TransportEvents = TransportEvents,
-	ObserverEvents extends TransportObserverEvents = TransportObserverEvents>
+export class Transport
+	<Events extends TransportEvents = TransportEvents,
+	ObserverEvents extends TransportObserverEvents = TransportObserverEvents,
+	TransportAppData extends AppData = AppData>
 	extends EnhancedEventEmitter<Events>
 {
 	// Internal data.
@@ -155,7 +158,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: TransportAppData;
 
 	// Method to retrieve Router RTP capabilities.
 	readonly #getRouterRtpCapabilities: () => RtpCapabilities;
@@ -208,7 +211,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 			getRouterRtpCapabilities,
 			getProducerById,
 			getDataProducerById
-		}: TransportConstructorOptions
+		}: TransportConstructorOptions<TransportAppData>
 	)
 	{
 		super();
@@ -219,7 +222,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 		this.#data = data;
 		this.channel = channel;
 		this.payloadChannel = payloadChannel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as TransportAppData;
 		this.#getRouterRtpCapabilities = getRouterRtpCapabilities;
 		this.getProducerById = getProducerById;
 		this.getDataProducerById = getDataProducerById;
@@ -244,17 +247,17 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): TransportAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: TransportAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
@@ -539,7 +542,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 	/**
 	 * Create a Producer.
 	 */
-	async produce(
+	async produce<ProducerAppData extends AppData = AppData>(
 		{
 			id = undefined,
 			kind,
@@ -547,8 +550,8 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 			paused = false,
 			keyFrameRequestDelay,
 			appData
-		}: ProducerOptions
-	): Promise<Producer>
+		}: ProducerOptions<ProducerAppData>
+	): Promise<Producer<ProducerAppData>>
 	{
 		logger.debug('produce()');
 
@@ -631,7 +634,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 			consumableRtpParameters
 		};
 
-		const producer = new Producer(
+		const producer = new Producer<ProducerAppData>(
 			{
 				internal :
 				{
@@ -665,7 +668,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 	 *
 	 * @virtual
 	 */
-	async consume(
+	async consume<ConsumerAppData extends AppData = AppData>(
 		{
 			producerId,
 			rtpCapabilities,
@@ -676,8 +679,8 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 			enableRtx,
 			pipe = false,
 			appData
-		}: ConsumerOptions
-	): Promise<Consumer>
+		}: ConsumerOptions<ConsumerAppData>
+	): Promise<Consumer<ConsumerAppData>>
 	{
 		logger.debug('consume()');
 
@@ -766,7 +769,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 			type : pipe ? 'pipe' : producer.type as ConsumerType
 		};
 
-		const consumer = new Consumer(
+		const consumer = new Consumer<ConsumerAppData>(
 			{
 				internal :
 				{
@@ -796,15 +799,15 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 	/**
 	 * Create a DataProducer.
 	 */
-	async produceData(
+	async produceData<DataProducerAppData extends AppData = AppData>(
 		{
 			id = undefined,
 			sctpStreamParameters,
 			label = '',
 			protocol = '',
 			appData
-		}: DataProducerOptions = {}
-	): Promise<DataProducer>
+		}: DataProducerOptions<DataProducerAppData> = {}
+	): Promise<DataProducer<DataProducerAppData>>
 	{
 		logger.debug('produceData()');
 
@@ -851,7 +854,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 		const data =
 			await this.channel.request('transport.produceData', this.internal.transportId, reqData);
 
-		const dataProducer = new DataProducer(
+		const dataProducer = new DataProducer<DataProducerAppData>(
 			{
 				internal :
 				{
@@ -882,15 +885,15 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 	/**
 	 * Create a DataConsumer.
 	 */
-	async consumeData(
+	async consumeData<ConsumerAppData extends AppData = AppData>(
 		{
 			dataProducerId,
 			ordered,
 			maxPacketLifeTime,
 			maxRetransmits,
 			appData
-		}: DataConsumerOptions
-	): Promise<DataConsumer>
+		}: DataConsumerOptions<ConsumerAppData>
+	): Promise<DataConsumer<ConsumerAppData>>
 	{
 		logger.debug('consumeData()');
 
@@ -975,7 +978,7 @@ export class Transport<Events extends TransportEvents = TransportEvents,
 		const data =
 			await this.channel.request('transport.consumeData', this.internal.transportId, reqData);
 
-		const dataConsumer = new DataConsumer(
+		const dataConsumer = new DataConsumer<ConsumerAppData>(
 			{
 				internal :
 				{
diff --git a/node/src/WebRtcServer.ts b/node/src/WebRtcServer.ts
index 3c0c4eb6b3..0db3346ded 100644
--- a/node/src/WebRtcServer.ts
+++ b/node/src/WebRtcServer.ts
@@ -3,6 +3,20 @@ import { EnhancedEventEmitter } from './EnhancedEventEmitter';
 import { Channel } from './Channel';
 import { TransportProtocol } from './Transport';
 import { WebRtcTransport } from './WebRtcTransport';
+import { AppData } from './types';
+
+export type WebRtcServerOptions<WebRtcServerAppData extends AppData = AppData> =
+{
+	/**
+	 * Listen infos.
+	 */
+	listenInfos: WebRtcServerListenInfo[];
+
+	/**
+	 * Custom application data.
+	 */
+	appData?: WebRtcServerAppData;
+};
 
 export type WebRtcServerListenInfo =
 {
@@ -28,19 +42,6 @@ export type WebRtcServerListenInfo =
 	port?: number;
 };
 
-export type WebRtcServerOptions =
-{
-	/**
-	 * Listen infos.
-	 */
-	listenInfos: WebRtcServerListenInfo[];
-
-	/**
-	 * Custom application data.
-	 */
-	appData?: Record<string, unknown>;
-};
-
 export type WebRtcServerEvents =
 { 
 	workerclose: [];
@@ -62,7 +63,8 @@ type WebRtcServerInternal =
 
 const logger = new Logger('WebRtcServer');
 
-export class WebRtcServer extends EnhancedEventEmitter<WebRtcServerEvents>
+export class WebRtcServer<WebRtcServerAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<WebRtcServerEvents>
 {
 	// Internal data.
 	readonly #internal: WebRtcServerInternal;
@@ -74,7 +76,7 @@ export class WebRtcServer extends EnhancedEventEmitter<WebRtcServerEvents>
 	#closed = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: WebRtcServerAppData;
 
 	// Transports map.
 	readonly #webRtcTransports: Map<string, WebRtcTransport> = new Map();
@@ -94,7 +96,7 @@ export class WebRtcServer extends EnhancedEventEmitter<WebRtcServerEvents>
 		{
 			internal: WebRtcServerInternal;
 			channel: Channel;
-			appData?: Record<string, unknown>;
+			appData?: WebRtcServerAppData;
 		}
 	)
 	{
@@ -104,7 +106,7 @@ export class WebRtcServer extends EnhancedEventEmitter<WebRtcServerEvents>
 
 		this.#internal = internal;
 		this.#channel = channel;
-		this.#appData = appData || {};
+		this.#appData = appData || {} as WebRtcServerAppData;
 	}
 
 	/**
@@ -126,17 +128,17 @@ export class WebRtcServer extends EnhancedEventEmitter<WebRtcServerEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): WebRtcServerAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: WebRtcServerAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
diff --git a/node/src/WebRtcTransport.ts b/node/src/WebRtcTransport.ts
index 8e364fed2e..e297a5d4a1 100644
--- a/node/src/WebRtcTransport.ts
+++ b/node/src/WebRtcTransport.ts
@@ -13,6 +13,10 @@ import {
 import { WebRtcServer } from './WebRtcServer';
 import { SctpParameters, NumSctpStreams } from './SctpParameters';
 import { Either } from './utils';
+import { AppData } from './types';
+
+export type WebRtcTransportOptions<WebRtcTransportAppData extends AppData = AppData> =
+	WebRtcTransportOptionsBase<WebRtcTransportAppData> & WebRtcTransportListen;
 
 export type WebRtcTransportListenIndividual =
 {
@@ -40,7 +44,7 @@ export type WebRtcTransportListenServer =
 export type WebRtcTransportListen =
 	Either<WebRtcTransportListenIndividual, WebRtcTransportListenServer>;
 
-export type WebRtcTransportOptionsBase =
+export type WebRtcTransportOptionsBase<WebRtcTransportAppData> =
 {
 	/**
 	 * Listen in UDP. Default true.
@@ -92,11 +96,9 @@ export type WebRtcTransportOptionsBase =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: WebRtcTransportAppData;
 };
 
-export type WebRtcTransportOptions = WebRtcTransportOptionsBase & WebRtcTransportListen;
-
 export type IceParameters =
 {
 	usernameFragment: string;
@@ -186,10 +188,11 @@ export type WebRtcTransportObserverEvents = TransportObserverEvents &
 	sctpstatechange: [SctpState];
 };
 
-type WebRtcTransportConstructorOptions = TransportConstructorOptions &
-{
-	data: WebRtcTransportData;
-};
+type WebRtcTransportConstructorOptions<WebRtcTransportAppData> =
+	TransportConstructorOptions<WebRtcTransportAppData> &
+	{
+		data: WebRtcTransportData;
+	};
 
 export type WebRtcTransportData =
 {
@@ -207,8 +210,8 @@ export type WebRtcTransportData =
 
 const logger = new Logger('WebRtcTransport');
 
-export class WebRtcTransport extends
-	Transport<WebRtcTransportEvents, WebRtcTransportObserverEvents>
+export class WebRtcTransport<WebRtcTransportAppData extends AppData = AppData>
+	extends Transport<WebRtcTransportEvents, WebRtcTransportObserverEvents, WebRtcTransportAppData>
 {
 	// WebRtcTransport data.
 	readonly #data: WebRtcTransportData;
@@ -216,7 +219,7 @@ export class WebRtcTransport extends
 	/**
 	 * @private
 	 */
-	constructor(options: WebRtcTransportConstructorOptions)
+	constructor(options: WebRtcTransportConstructorOptions<WebRtcTransportAppData>)
 	{
 		super(options);
 
diff --git a/node/src/Worker.ts b/node/src/Worker.ts
index eefa9c8018..582a0f12b9 100644
--- a/node/src/Worker.ts
+++ b/node/src/Worker.ts
@@ -9,6 +9,7 @@ import { Channel } from './Channel';
 import { PayloadChannel } from './PayloadChannel';
 import { Router, RouterOptions } from './Router';
 import { WebRtcServer, WebRtcServerOptions } from './WebRtcServer';
+import { AppData } from './types';
 
 export type WorkerLogLevel = 'debug' | 'warn' | 'error' | 'none';
 
@@ -27,7 +28,7 @@ export type WorkerLogTag =
   | 'sctp'
   | 'message';
 
-export type WorkerSettings =
+export type WorkerSettings<WorkerAppData extends AppData = AppData> =
 {
 	/**
 	 * Logging level for logs generated by the media worker subprocesses (check
@@ -77,10 +78,11 @@ export type WorkerSettings =
 	/**
 	 * Custom application data.
 	 */
-	appData?: Record<string, unknown>;
+	appData?: WorkerAppData;
 };
 
-export type WorkerUpdateableSettings = Pick<WorkerSettings, 'logLevel' | 'logTags'>;
+export type WorkerUpdateableSettings<T extends AppData = AppData> =
+	Pick<WorkerSettings<T>, 'logLevel' | 'logTags'>;
 
 /**
  * An object with the fields of the uv_rusage_t struct.
@@ -202,7 +204,8 @@ const workerBin = process.env.MEDIASOUP_WORKER_BIN
 const logger = new Logger('Worker');
 const workerLogger = new Logger('Worker');
 
-export class Worker extends EnhancedEventEmitter<WorkerEvents>
+export class Worker<WorkerAppData extends AppData = AppData>
+	extends EnhancedEventEmitter<WorkerEvents>
 {
 	// mediasoup-worker child process.
 	#child?: ChildProcess;
@@ -223,7 +226,7 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 	#died = false;
 
 	// Custom app data.
-	readonly #appData: Record<string, unknown>;
+	#appData: WorkerAppData;
 
 	// WebRtcServers set.
 	readonly #webRtcServers: Set<WebRtcServer> = new Set();
@@ -247,7 +250,7 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 			dtlsPrivateKeyFile,
 			libwebrtcFieldTrials,
 			appData
-		}: WorkerSettings)
+		}: WorkerSettings<WorkerAppData>)
 	{
 		super();
 
@@ -356,7 +359,7 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 				consumerSocket : this.#child.stdio[6]
 			});
 
-		this.#appData = appData || {};
+		this.#appData = appData || {} as WorkerAppData;
 
 		let spawnDone = false;
 
@@ -487,17 +490,17 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 	/**
 	 * App custom data.
 	 */
-	get appData(): Record<string, unknown>
+	get appData(): WorkerAppData
 	{
 		return this.#appData;
 	}
 
 	/**
-	 * Invalid setter.
+	 * App custom data setter.
 	 */
-	set appData(appData: Record<string, unknown>) // eslint-disable-line no-unused-vars
+	set appData(appData: WorkerAppData)
 	{
-		throw new Error('cannot override appData object');
+		this.#appData = appData;
 	}
 
 	/**
@@ -603,7 +606,7 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 		{
 			logLevel,
 			logTags
-		}: WorkerUpdateableSettings = {}
+		}: WorkerUpdateableSettings<WorkerAppData> = {}
 	): Promise<void>
 	{
 		logger.debug('updateSettings()');
@@ -616,11 +619,12 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 	/**
 	 * Create a WebRtcServer.
 	 */
-	async createWebRtcServer(
+	async createWebRtcServer<WebRtcServerAppData extends AppData = AppData>(
 		{
 			listenInfos,
 			appData
-		}: WebRtcServerOptions): Promise<WebRtcServer>
+		}: WebRtcServerOptions<WebRtcServerAppData>
+	): Promise<WebRtcServer<WebRtcServerAppData>>
 	{
 		logger.debug('createWebRtcServer()');
 
@@ -656,11 +660,11 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 	/**
 	 * Create a Router.
 	 */
-	async createRouter(
+	async createRouter<RouterAppData extends AppData = AppData>(
 		{
 			mediaCodecs,
 			appData
-		}: RouterOptions = {}): Promise<Router>
+		}: RouterOptions<RouterAppData> = {}): Promise<Router<RouterAppData>>
 	{
 		logger.debug('createRouter()');
 
@@ -677,7 +681,7 @@ export class Worker extends EnhancedEventEmitter<WorkerEvents>
 		await this.#channel.request('worker.createRouter', undefined, reqData);
 
 		const data = { rtpCapabilities };
-		const router = new Router(
+		const router = new Router<RouterAppData>(
 			{
 				internal :
 				{
diff --git a/node/src/index.ts b/node/src/index.ts
index 83d7967760..c98d349e7b 100644
--- a/node/src/index.ts
+++ b/node/src/index.ts
@@ -5,6 +5,7 @@ import * as utils from './utils';
 import { supportedRtpCapabilities } from './supportedRtpCapabilities';
 import { RtpCapabilities } from './RtpParameters';
 import * as types from './types';
+import { AppData } from './types';
 
 /**
  * Expose all types.
@@ -38,7 +39,7 @@ export { observer };
 /**
  * Create a Worker.
  */
-export async function createWorker(
+export async function createWorker<WorkerAppData extends AppData = AppData>(
 	{
 		logLevel = 'error',
 		logTags,
@@ -48,8 +49,8 @@ export async function createWorker(
 		dtlsPrivateKeyFile,
 		libwebrtcFieldTrials,
 		appData
-	}: WorkerSettings = {}
-): Promise<Worker>
+	}: WorkerSettings<WorkerAppData> = {}
+): Promise<Worker<WorkerAppData>>
 {
 	logger.debug('createWorker()');
 
@@ -58,7 +59,7 @@ export async function createWorker(
 		throw new TypeError('if given, appData must be an object');
 	}
 
-	const worker = new Worker(
+	const worker = new Worker<WorkerAppData>(
 		{
 			logLevel,
 			logTags,
diff --git a/node/src/ortc.ts b/node/src/ortc.ts
index 9b0995b1e3..6f229e6743 100644
--- a/node/src/ortc.ts
+++ b/node/src/ortc.ts
@@ -435,9 +435,8 @@ export function validateRtpCodecParameters(codec: RtpCodecParameters): void
 }
 
 /**
- * Validates RtpHeaderExtensionParameteters. It may modify given data by adding missing
- * fields with default values.
- * It throws if invalid.
+ * Validates RtpHeaderExtensionParameteters. It may modify given data by adding
+ * missing fields with default values. It throws if invalid.
  */
 export function validateRtpHeaderExtensionParameters(
 	ext: RtpHeaderExtensionParameters
diff --git a/node/src/tests/test-Router.ts b/node/src/tests/test-Router.ts
index c9316ee1f4..9d9941f2b4 100644
--- a/node/src/tests/test-Router.ts
+++ b/node/src/tests/test-Router.ts
@@ -48,7 +48,11 @@ test('worker.createRouter() succeeds', async () =>
 
 	worker.observer.once('newrouter', onObserverNewRouter);
 
-	const router = await worker.createRouter({ mediaCodecs, appData: { foo: 123 } });
+	const router = await worker.createRouter<{ foo: number; bar?: string }>(
+		{
+			mediaCodecs,
+			appData : { foo: 123 }
+		});
 
 	expect(onObserverNewRouter).toHaveBeenCalledTimes(1);
 	expect(onObserverNewRouter).toHaveBeenCalledWith(router);
@@ -59,6 +63,8 @@ test('worker.createRouter() succeeds', async () =>
 	expect(Array.isArray(router.rtpCapabilities.headerExtensions)).toBe(true);
 	expect(router.appData).toEqual({ foo: 123 });
 
+	expect(() => (router.appData = { foo: 222, bar: 'BBB' })).not.toThrow();
+
 	await expect(worker.dump())
 		.resolves
 		.toEqual(
diff --git a/node/src/tests/test-WebRtcServer.ts b/node/src/tests/test-WebRtcServer.ts
index febdea95bf..ff28ebe26b 100644
--- a/node/src/tests/test-WebRtcServer.ts
+++ b/node/src/tests/test-WebRtcServer.ts
@@ -21,7 +21,7 @@ test('worker.createWebRtcServer() succeeds', async () =>
 	const port1 = await pickPort({ ip: '127.0.0.1', reserveTimeout: 0 });
 	const port2 = await pickPort({ type: 'tcp', ip: '127.0.0.1', reserveTimeout: 0 });
 
-	const webRtcServer = await worker.createWebRtcServer(
+	const webRtcServer = await worker.createWebRtcServer<{ foo?: number }>(
 		{
 			listenInfos :
 			[
diff --git a/node/src/tests/test-Worker.ts b/node/src/tests/test-Worker.ts
index feb0232fcc..15ab5ace52 100644
--- a/node/src/tests/test-Worker.ts
+++ b/node/src/tests/test-Worker.ts
@@ -32,7 +32,7 @@ test('createWorker() succeeds', async () =>
 	expect(worker.died).toBe(false);
 
 	// eslint-disable-next-line require-atomic-updates
-	worker = await createWorker(
+	worker = await createWorker<{ foo: number; bar?: string }>(
 		{
 			logLevel             : 'debug',
 			logTags              : [ 'info' ],
@@ -41,13 +41,13 @@ test('createWorker() succeeds', async () =>
 			dtlsCertificateFile  : path.join(__dirname, 'data', 'dtls-cert.pem'),
 			dtlsPrivateKeyFile   : path.join(__dirname, 'data', 'dtls-key.pem'),
 			libwebrtcFieldTrials : 'WebRTC-Bwe-AlrLimitedBackoff/Disabled/',
-			appData              : { bar: 456 }
+			appData              : { foo: 456 }
 		});
 	expect(worker.constructor.name).toBe('Worker');
 	expect(typeof worker.pid).toBe('number');
 	expect(worker.closed).toBe(false);
 	expect(worker.died).toBe(false);
-	expect(worker.appData).toEqual({ bar: 456 });
+	expect(worker.appData).toEqual({ foo: 456 });
 
 	worker.close();
 
diff --git a/node/src/types.ts b/node/src/types.ts
index b3fe195f77..fe72cb95fb 100644
--- a/node/src/types.ts
+++ b/node/src/types.ts
@@ -18,3 +18,8 @@ export * from './SctpParameters';
 export * from './SrtpParameters';
 export * from './errors';
 export { ScalabilityMode } from './scalabilityModes';
+
+export type AppData =
+{
+	[key: string]: unknown;
+};
diff --git a/worker/test/src/RTC/TestRtpRetransmissionBuffer.cpp b/worker/test/src/RTC/TestRtpRetransmissionBuffer.cpp
index 74d2628b44..411db9fcac 100644
--- a/worker/test/src/RTC/TestRtpRetransmissionBuffer.cpp
+++ b/worker/test/src/RTC/TestRtpRetransmissionBuffer.cpp
@@ -266,8 +266,6 @@ SCENARIO("RtpRetransmissionBuffer", "[rtp][rtx]")
 		myRetransmissionBuffer.Insert(33332, 1000000002);
 		myRetransmissionBuffer.Insert(33330, 1000000003);
 
-		myRetransmissionBuffer.Dump();
-
 		// clang-format off
 		myRetransmissionBuffer.AssertBuffer(
 			{