diff --git a/examples/cli-chat/src/chat.ts b/examples/cli-chat/src/chat.ts
index 07150b2fa6..d11f00fdd9 100644
--- a/examples/cli-chat/src/chat.ts
+++ b/examples/cli-chat/src/chat.ts
@@ -6,7 +6,6 @@ import { multiaddr, Multiaddr } from 'multiaddr';
 import { ChatMessage } from 'waku/chat_message';
 import Waku from 'waku/waku';
 import { WakuMessage } from 'waku/waku_message';
-import { RelayDefaultTopic } from 'waku/waku_relay';
 import { StoreCodec } from 'waku/waku_store';
 
 const ChatContentTopic = 'dingpu';
@@ -43,15 +42,15 @@ export default async function startChat(): Promise<void> {
 
   console.log(`Hi, ${nick}!`);
 
-  // TODO: Bubble event to waku, infer topic, decode msg
-  // Tracked with https://github.com/status-im/js-waku/issues/19
-  waku.libp2p.pubsub.on(RelayDefaultTopic, (event) => {
-    const wakuMsg = WakuMessage.decode(event.data);
-    if (wakuMsg.payload) {
-      const chatMsg = ChatMessage.decode(wakuMsg.payload);
-      console.log(formatMessage(chatMsg));
-    }
-  });
+  waku.relay.addObserver(
+    (message) => {
+      if (message.payload) {
+        const chatMsg = ChatMessage.decode(message.payload);
+        console.log(formatMessage(chatMsg));
+      }
+    },
+    [ChatContentTopic]
+  );
 
   if (opts.staticNode) {
     console.log(`Dialing ${opts.staticNode}`);
diff --git a/examples/web-chat/src/App.tsx b/examples/web-chat/src/App.tsx
index e2ec3b68ee..d25a3415fd 100644
--- a/examples/web-chat/src/App.tsx
+++ b/examples/web-chat/src/App.tsx
@@ -5,7 +5,6 @@ import './App.css';
 import { ChatMessage } from './ChatMessage';
 import { ChatMessage as WakuChatMessage } from 'waku/chat_message';
 import { WakuMessage } from 'waku/waku_message';
-import { RelayDefaultTopic } from 'waku/waku_relay';
 import { StoreCodec } from 'waku/waku_store';
 import handleCommand from './command';
 import Room from './Room';
@@ -52,10 +51,14 @@ export default function App() {
   let [nick, setNick] = useState<string>(generate());
 
   useEffect(() => {
-    const handleRelayMessage = (event: { data: Uint8Array }) => {
-      const chatMsg = decodeWakuMessage(event.data);
-      if (chatMsg) {
-        setNewMessages([chatMsg]);
+    const handleRelayMessage = (wakuMsg: WakuMessage) => {
+      if (wakuMsg.payload) {
+        const chatMsg = ChatMessage.fromWakuChatMessage(
+          WakuChatMessage.decode(wakuMsg.payload)
+        );
+        if (chatMsg) {
+          setNewMessages([chatMsg]);
+        }
       }
     };
 
@@ -94,7 +97,7 @@ export default function App() {
         .then(() => console.log('Waku init done'))
         .catch((e) => console.log('Waku init failed ', e));
     } else {
-      stateWaku.libp2p.pubsub.on(RelayDefaultTopic, handleRelayMessage);
+      stateWaku.relay.addObserver(handleRelayMessage, [ChatContentTopic]);
 
       stateWaku.libp2p.peerStore.on(
         'change:protocols',
@@ -103,10 +106,6 @@ export default function App() {
 
       // To clean up listener when component unmounts
       return () => {
-        stateWaku?.libp2p.pubsub.removeListener(
-          RelayDefaultTopic,
-          handleRelayMessage
-        );
         stateWaku?.libp2p.peerStore.removeListener(
           'change:protocols',
           handleProtocolChange.bind({}, stateWaku)
@@ -173,13 +172,3 @@ async function initWaku(setter: (waku: Waku) => void) {
     console.log('Issue starting waku ', e);
   }
 }
-
-function decodeWakuMessage(data: Uint8Array): null | ChatMessage {
-  const wakuMsg = WakuMessage.decode(data);
-  if (!wakuMsg.payload) {
-    return null;
-  }
-  return ChatMessage.fromWakuChatMessage(
-    WakuChatMessage.decode(wakuMsg.payload)
-  );
-}
diff --git a/src/lib/waku_message.ts b/src/lib/waku_message.ts
index cb1331c537..407a093fea 100644
--- a/src/lib/waku_message.ts
+++ b/src/lib/waku_message.ts
@@ -4,8 +4,8 @@ import { Reader } from 'protobufjs/minimal';
 // Protecting the user from protobuf oddities
 import * as proto from '../proto/waku/v2/message';
 
-export const DEFAULT_CONTENT_TOPIC = '/waku/2/default-content/proto';
-const DEFAULT_VERSION = 0;
+export const DefaultContentTopic = '/waku/2/default-content/proto';
+const DefaultVersion = 0;
 
 export class WakuMessage {
   public constructor(public proto: proto.WakuMessage) {}
@@ -18,12 +18,12 @@ export class WakuMessage {
    */
   static fromUtf8String(
     utf8: string,
-    contentTopic: string = DEFAULT_CONTENT_TOPIC
+    contentTopic: string = DefaultContentTopic
   ): WakuMessage {
     const payload = Buffer.from(utf8, 'utf-8');
     return new WakuMessage({
       payload,
-      version: DEFAULT_VERSION,
+      version: DefaultVersion,
       contentTopic,
     });
   }
@@ -36,11 +36,11 @@ export class WakuMessage {
    */
   static fromBytes(
     payload: Uint8Array,
-    contentTopic: string = DEFAULT_CONTENT_TOPIC
+    contentTopic: string = DefaultContentTopic
   ): WakuMessage {
     return new WakuMessage({
       payload,
-      version: DEFAULT_VERSION,
+      version: DefaultVersion,
       contentTopic,
     });
   }
diff --git a/src/lib/waku_relay/index.spec.ts b/src/lib/waku_relay/index.spec.ts
index 2e8eada2e5..1b5a3d4609 100644
--- a/src/lib/waku_relay/index.spec.ts
+++ b/src/lib/waku_relay/index.spec.ts
@@ -1,5 +1,4 @@
 import { expect } from 'chai';
-import Pubsub from 'libp2p-interfaces/src/pubsub';
 import TCP from 'libp2p-tcp';
 
 import {
@@ -72,19 +71,56 @@ describe('Waku Relay', () => {
   it('Publish', async function () {
     this.timeout(10000);
 
-    const message = WakuMessage.fromUtf8String('JS to JS communication works');
+    const messageText = 'JS to JS communication works';
+    const message = WakuMessage.fromUtf8String(messageText);
 
-    const receivedPromise = waitForNextData(waku2.libp2p.pubsub);
+    const receivedMsgPromise: Promise<WakuMessage> = new Promise((resolve) => {
+      waku2.relay.addObserver(resolve);
+    });
 
     await waku1.relay.send(message);
 
-    const receivedMsg = await receivedPromise;
+    const receivedMsg = await receivedMsgPromise;
 
     expect(receivedMsg.contentTopic).to.eq(message.contentTopic);
     expect(receivedMsg.version).to.eq(message.version);
+    expect(receivedMsg.payloadAsUtf8).to.eq(messageText);
+  });
 
-    const payload = Buffer.from(receivedMsg.payload!);
-    expect(Buffer.compare(payload, message.payload!)).to.eq(0);
+  it('Filter on content topics', async function () {
+    this.timeout(10000);
+
+    const fooMessageText = 'Published on content topic foo';
+    const barMessageText = 'Published on content topic bar';
+    const fooMessage = WakuMessage.fromUtf8String(fooMessageText, 'foo');
+    const barMessage = WakuMessage.fromUtf8String(barMessageText, 'bar');
+
+    const receivedBarMsgPromise: Promise<WakuMessage> = new Promise(
+      (resolve) => {
+        waku2.relay.addObserver(resolve, ['bar']);
+      }
+    );
+
+    const allMessages: WakuMessage[] = [];
+    waku2.relay.addObserver((wakuMsg) => {
+      allMessages.push(wakuMsg);
+    });
+
+    await waku1.relay.send(fooMessage);
+    await waku1.relay.send(barMessage);
+
+    const receivedBarMsg = await receivedBarMsgPromise;
+
+    expect(receivedBarMsg.contentTopic).to.eq(barMessage.contentTopic);
+    expect(receivedBarMsg.version).to.eq(barMessage.version);
+    expect(receivedBarMsg.payloadAsUtf8).to.eq(barMessageText);
+    expect(allMessages.length).to.eq(2);
+    expect(allMessages[0].contentTopic).to.eq(fooMessage.contentTopic);
+    expect(allMessages[0].version).to.eq(fooMessage.version);
+    expect(allMessages[0].payloadAsUtf8).to.eq(fooMessageText);
+    expect(allMessages[1].contentTopic).to.eq(barMessage.contentTopic);
+    expect(allMessages[1].version).to.eq(barMessage.version);
+    expect(allMessages[1].payloadAsUtf8).to.eq(barMessageText);
   });
 
   describe('Interop: Nim', function () {
@@ -126,7 +162,8 @@ describe('Waku Relay', () => {
       it('Js publishes to nim', async function () {
         this.timeout(5000);
 
-        const message = WakuMessage.fromUtf8String('This is a message');
+        const messageText = 'This is a message';
+        const message = WakuMessage.fromUtf8String(messageText);
 
         await waku.relay.send(message);
 
@@ -139,26 +176,27 @@ describe('Waku Relay', () => {
 
         expect(msgs[0].contentTopic).to.equal(message.contentTopic);
         expect(msgs[0].version).to.equal(message.version);
-
-        const payload = Buffer.from(msgs[0].payload!);
-        expect(Buffer.compare(payload, message.payload!)).to.equal(0);
+        expect(msgs[0].payloadAsUtf8).to.equal(messageText);
       });
 
       it('Nim publishes to js', async function () {
         this.timeout(5000);
-        const message = WakuMessage.fromUtf8String('Here is another message.');
+        const messageText = 'Here is another message.';
+        const message = WakuMessage.fromUtf8String(messageText);
 
-        const receivedPromise = waitForNextData(waku.libp2p.pubsub);
+        const receivedMsgPromise: Promise<WakuMessage> = new Promise(
+          (resolve) => {
+            waku.relay.addObserver(resolve);
+          }
+        );
 
         await nimWaku.sendMessage(message);
 
-        const receivedMsg = await receivedPromise;
+        const receivedMsg = await receivedMsgPromise;
 
         expect(receivedMsg.contentTopic).to.eq(message.contentTopic);
         expect(receivedMsg.version).to.eq(message.version);
-
-        const payload = Buffer.from(receivedMsg.payload!);
-        expect(Buffer.compare(payload, message.payload!)).to.eq(0);
+        expect(receivedMsg.payloadAsUtf8).to.eq(messageText);
       });
     });
 
@@ -209,7 +247,8 @@ describe('Waku Relay', () => {
       it('Js publishes to nim', async function () {
         this.timeout(30000);
 
-        const message = WakuMessage.fromUtf8String('This is a message');
+        const messageText = 'This is a message';
+        const message = WakuMessage.fromUtf8String(messageText);
         await delay(1000);
         await waku.relay.send(message);
 
@@ -223,27 +262,28 @@ describe('Waku Relay', () => {
 
         expect(msgs[0].contentTopic).to.equal(message.contentTopic);
         expect(msgs[0].version).to.equal(message.version);
-
-        const payload = Buffer.from(msgs[0].payload!);
-        expect(Buffer.compare(payload, message.payload!)).to.equal(0);
+        expect(msgs[0].payloadAsUtf8).to.equal(messageText);
       });
 
       it('Nim publishes to js', async function () {
         await delay(200);
 
-        const message = WakuMessage.fromUtf8String('Here is another message.');
+        const messageText = 'Here is another message.';
+        const message = WakuMessage.fromUtf8String(messageText);
 
-        const receivedPromise = waitForNextData(waku.libp2p.pubsub);
+        const receivedMsgPromise: Promise<WakuMessage> = new Promise(
+          (resolve) => {
+            waku.relay.addObserver(resolve);
+          }
+        );
 
         await nimWaku.sendMessage(message);
 
-        const receivedMsg = await receivedPromise;
+        const receivedMsg = await receivedMsgPromise;
 
         expect(receivedMsg.contentTopic).to.eq(message.contentTopic);
         expect(receivedMsg.version).to.eq(message.version);
-
-        const payload = Buffer.from(receivedMsg.payload!);
-        expect(Buffer.compare(payload, message.payload!)).to.eq(0);
+        expect(receivedMsg.payloadAsUtf8).to.eq(messageText);
       });
     });
 
@@ -313,21 +353,18 @@ describe('Waku Relay', () => {
         const msgStr = 'Hello there!';
         const message = WakuMessage.fromUtf8String(msgStr);
 
-        const waku2ReceivedPromise = waitForNextData(waku2.libp2p.pubsub);
+        const waku2ReceivedMsgPromise: Promise<WakuMessage> = new Promise(
+          (resolve) => {
+            waku2.relay.addObserver(resolve);
+          }
+        );
 
         await waku1.relay.send(message);
         console.log('Waiting for message');
-        const waku2ReceivedMsg = await waku2ReceivedPromise;
+        const waku2ReceivedMsg = await waku2ReceivedMsgPromise;
 
         expect(waku2ReceivedMsg.payloadAsUtf8).to.eq(msgStr);
       });
     });
   });
 });
-
-async function waitForNextData(pubsub: Pubsub): Promise<WakuMessage> {
-  const msg = (await new Promise((resolve) => {
-    pubsub.once(RelayDefaultTopic, resolve);
-  })) as Pubsub.InMessage;
-  return WakuMessage.decode(msg.data);
-}
diff --git a/src/lib/waku_relay/index.ts b/src/lib/waku_relay/index.ts
index dccec6eeae..495bdda27b 100644
--- a/src/lib/waku_relay/index.ts
+++ b/src/lib/waku_relay/index.ts
@@ -12,7 +12,7 @@ import {
   messageIdToString,
   shuffle,
 } from 'libp2p-gossipsub/src/utils';
-import { InMessage } from 'libp2p-interfaces/src/pubsub';
+import Pubsub, { InMessage } from 'libp2p-interfaces/src/pubsub';
 import { SignaturePolicy } from 'libp2p-interfaces/src/pubsub/signature-policy';
 import PeerId from 'peer-id';
 
@@ -26,7 +26,7 @@ export * from './constants';
 export * from './relay_heartbeat';
 
 /**
- * See GossipOptions from libp2p-gossipsub
+ * See {GossipOptions} from libp2p-gossipsub
  */
 interface GossipOptions {
   emitSelf: boolean;
@@ -48,8 +48,21 @@ interface GossipOptions {
   Dlazy: number;
 }
 
-export class WakuRelay extends Gossipsub {
+/**
+ * Implements the [Waku v2 Relay protocol]{@link https://rfc.vac.dev/spec/11/}.
+ * Must be passed as a `pubsub` module to a {Libp2p} instance.
+ *
+ * @implements {Pubsub}
+ */
+export class WakuRelay extends Gossipsub implements Pubsub {
   heartbeat: RelayHeartbeat;
+  /**
+   * observers called when receiving new message.
+   * Observers under key "" are always called.
+   */
+  public observers: {
+    [contentTopic: string]: Array<(message: WakuMessage) => void>;
+  };
 
   /**
    *
@@ -66,6 +79,7 @@ export class WakuRelay extends Gossipsub {
     );
 
     this.heartbeat = new RelayHeartbeat(this);
+    this.observers = {};
 
     const multicodecs = [constants.RelayCodec];
 
@@ -74,28 +88,76 @@ export class WakuRelay extends Gossipsub {
 
   /**
    * Mounts the gossipsub protocol onto the libp2p node
-   * and subscribes to the default topic
+   * and subscribes to the default topic.
+   *
    * @override
    * @returns {void}
    */
-  start(): void {
+  public start(): void {
+    this.on(constants.RelayDefaultTopic, (event) => {
+      const wakuMsg = WakuMessage.decode(event.data);
+      if (this.observers['']) {
+        this.observers[''].forEach((callbackFn) => {
+          callbackFn(wakuMsg);
+        });
+      }
+      if (wakuMsg.contentTopic) {
+        if (this.observers[wakuMsg.contentTopic]) {
+          this.observers[wakuMsg.contentTopic].forEach((callbackFn) => {
+            callbackFn(wakuMsg);
+          });
+        }
+      }
+    });
+
     super.start();
     super.subscribe(constants.RelayDefaultTopic);
   }
 
   /**
-   * Send Waku messages under default topic
-   * @override
+   * Send Waku message.
+   *
    * @param {WakuMessage} message
    * @returns {Promise<void>}
    */
-  async send(message: WakuMessage): Promise<void> {
+  public async send(message: WakuMessage): Promise<void> {
     const msg = message.encode();
     await super.publish(constants.RelayDefaultTopic, Buffer.from(msg));
   }
 
   /**
-   * Join topic
+   * Register an observer of new messages received via waku relay
+   *
+   * @param callback called when a new message is received via waku relay
+   * @param contentTopics Content Topics for which the callback with be called,
+   * all of them if undefined, [] or ["",..] is passed.
+   * @returns {void}
+   */
+  addObserver(
+    callback: (message: WakuMessage) => void,
+    contentTopics: string[] = []
+  ): void {
+    if (contentTopics.length === 0) {
+      if (!this.observers['']) {
+        this.observers[''] = [];
+      }
+      this.observers[''].push(callback);
+    } else {
+      contentTopics.forEach((contentTopic) => {
+        if (!this.observers[contentTopic]) {
+          this.observers[contentTopic] = [];
+        }
+        this.observers[contentTopic].push(callback);
+      });
+    }
+  }
+
+  /**
+   * Join pubsub topic.
+   * This is present to override the behavior of Gossipsub and should not
+   * be used by API Consumers
+   *
+   * @ignore
    * @param {string} topic
    * @returns {void}
    * @override
@@ -152,8 +214,11 @@ export class WakuRelay extends Gossipsub {
   }
 
   /**
-   * Publish messages
+   * Publish messages.
+   * This is present to override the behavior of Gossipsub and should not
+   * be used by API Consumers
    *
+   * @ignore
    * @override
    * @param {InMessage} msg
    * @returns {void}
@@ -222,7 +287,13 @@ export class WakuRelay extends Gossipsub {
   }
 
   /**
-   * Emits gossip to peers in a particular topic
+   * Emits gossip to peers in a particular topic.
+   *
+   * This is present to override the behavior of Gossipsub and should not
+   * be used by API Consumers
+   *
+   * @ignore
+   * @override
    * @param {string} topic
    * @param {Set<string>} exclude peers to exclude
    * @returns {void}
@@ -300,7 +371,12 @@ export class WakuRelay extends Gossipsub {
   }
 
   /**
-   * Make a PRUNE control message for a peer in a topic
+   * Make a PRUNE control message for a peer in a topic.
+   * This is present to override the behavior of Gossipsub and should not
+   * be used by API Consumers
+   *
+   * @ignore
+   * @override
    * @param {string} id
    * @param {string} topic
    * @param {boolean} doPX
diff --git a/src/lib/waku_store/history_rpc.ts b/src/lib/waku_store/history_rpc.ts
index 8adb105616..3e3fdb537a 100644
--- a/src/lib/waku_store/history_rpc.ts
+++ b/src/lib/waku_store/history_rpc.ts
@@ -2,14 +2,14 @@ import { Reader } from 'protobufjs/minimal';
 import { v4 as uuid } from 'uuid';
 
 import * as proto from '../../proto/waku/v2/store';
-import { DEFAULT_CONTENT_TOPIC } from '../waku_message';
+import { DefaultContentTopic } from '../waku_message';
 import { RelayDefaultTopic } from '../waku_relay';
 
 export class HistoryRPC {
   public constructor(public proto: proto.HistoryRPC) {}
 
   static createQuery(
-    contentTopics: string[] = [DEFAULT_CONTENT_TOPIC],
+    contentTopics: string[] = [DefaultContentTopic],
     cursor?: proto.Index,
     pubsubTopic: string = RelayDefaultTopic
   ): HistoryRPC {
diff --git a/src/test_utils/nim_waku.ts b/src/test_utils/nim_waku.ts
index 34ac85ab61..3096463076 100644
--- a/src/test_utils/nim_waku.ts
+++ b/src/test_utils/nim_waku.ts
@@ -9,6 +9,7 @@ import PeerId from 'peer-id';
 
 import { WakuMessage } from '../lib/waku_message';
 import { RelayDefaultTopic } from '../lib/waku_relay';
+import * as proto from '../proto/waku/v2/message';
 
 import { existsAsync, mkdirAsync, openAsync } from './async_fs';
 import waitForLine from './log_file';
@@ -167,9 +168,9 @@ export class NimWaku {
   async messages(): Promise<WakuMessage[]> {
     this.checkProcess();
 
-    return this.rpcCall<WakuMessage[]>('get_waku_v2_relay_v1_messages', [
+    return this.rpcCall<proto.WakuMessage[]>('get_waku_v2_relay_v1_messages', [
       RelayDefaultTopic,
-    ]);
+    ]).then((msgs) => msgs.map((protoMsg) => new WakuMessage(protoMsg)));
   }
 
   async getPeerId(): Promise<PeerId> {