diff --git a/packages/status-js/src/client/activityCenter.ts b/packages/status-js/src/client/activityCenter.ts
new file mode 100644
index 00000000..36eb8b36
--- /dev/null
+++ b/packages/status-js/src/client/activityCenter.ts
@@ -0,0 +1,125 @@
+// todo: rename to notifications (center?), inbox, or keep same as other platforms
+import type { ChatMessage } from './chat'
+// import type { Client } from './client'
+
+// todo?: union
+// todo?: rename to Activity
+type Notification = {
+  // fixme?: specify message type (message_reply)
+  type: 'message'
+  value: ChatMessage
+}
+
+type ActivityCenterLatest = {
+  notifications: Notification[]
+  // todo?: rename count to mentionsAndRepliesCount
+  unreadChats: Map<string, { count: number }> // id, count (mentions, replies)
+}
+
+// todo?: rename to NotificationCenter
+export class ActivityCenter {
+  // todo?: use client.account for mentions and replies, or in chat.ts
+  // #client: Client
+
+  #notifications: Set<Notification>
+  #callbacks: Set<(latest: ActivityCenterLatest) => void>
+
+  constructor(/* client: Client */) {
+    // this.#client = client
+
+    this.#notifications = new Set()
+    this.#callbacks = new Set()
+  }
+
+  // todo?: rename to latest, change
+  public getLatest = (): ActivityCenterLatest => {
+    const notifications: Notification[] = []
+    const unreadChats: Map<string, { count: number }> = new Map()
+
+    for (const notification of this.#notifications.values()) {
+      // todo?: switch
+      if (notification.type === 'message') {
+        const chatUuid = notification.value.chatUuid
+
+        const chat = unreadChats.get(chatUuid)
+        if (chat) {
+          // fixme!: isReply || isMention
+          const shouldIncrement = false
+          if (shouldIncrement) {
+            chat.count++
+          }
+        } else {
+          unreadChats.set(chatUuid, { count: 0 })
+        }
+      }
+
+      notifications.push(notification)
+    }
+
+    // todo?: reverse order
+    notifications.sort((a, b) => {
+      if (a.value.clock < b.value.clock) {
+        return -1
+      }
+
+      if (a.value.clock > b.value.clock) {
+        return 1
+      }
+
+      return 0
+    })
+
+    // fixme!?: do not display regular messages, only mentions and replies
+    // todo?: group notifications (all, unreads, mentions, replies, _chats.{id,count})
+    return { notifications, unreadChats }
+  }
+
+  public addMessageNotification = (value: ChatMessage) => {
+    this.#notifications.add({ type: 'message', value })
+
+    this.emitLatest()
+  }
+
+  /**
+   * Removes all notifications.
+   */
+  removeNotifications = () => {
+    this.#notifications.clear()
+
+    this.emitLatest()
+  }
+
+  /**
+   * Removes chat message notifications from the Activity Center. For example,
+   * on only opening or after scrolling to the end.
+   */
+  public removeChatNotifications = (chatUuid: string) => {
+    // todo?: add chatUuid to "readChats" Set instead and resolve in getNotifications
+    // triggered by following emit, and clear the set afterwards
+    for (const notification of this.#notifications) {
+      if (notification.type !== 'message') {
+        continue
+      }
+
+      if (notification.value.chatUuid === chatUuid) {
+        this.#notifications.delete(notification)
+      }
+    }
+
+    this.emitLatest()
+  }
+
+  private emitLatest = () => {
+    const latest = this.getLatest()
+
+    this.#callbacks.forEach(callback => callback(latest))
+  }
+
+  public onChange = (callback: (latest: ActivityCenterLatest) => void) => {
+    this.#callbacks.add(callback)
+
+    return () => {
+      this.#callbacks.delete(callback)
+    }
+  }
+}
diff --git a/packages/status-js/src/client/chat.ts b/packages/status-js/src/client/chat.ts
index 36fc3971..67b2613b 100644
--- a/packages/status-js/src/client/chat.ts
+++ b/packages/status-js/src/client/chat.ts
@@ -35,7 +35,9 @@ export type ChatMessage = ChatMessageProto & {
 
 type FetchedMessage = { messageId: string; timestamp?: Date }
 
+// todo?: add isMuted prop, use as condition to add a message/notification to activity center or not
 export class Chat {
+  // todo: use #
   private readonly client: Client
   #clock: bigint
 
@@ -51,6 +53,7 @@ export class Chat {
   #pinEvents: Map<string, Pick<ChatMessage, 'clock' | 'pinned'>>
   #reactEvents: Map<string, Pick<ChatMessage, 'clock' | 'reactions'>>
   #deleteEvents: Map<string, Pick<ChatMessage, 'clock' | 'signer'>>
+  #isActive: boolean
   #fetchingMessages?: boolean
   #previousFetchedStartTime?: Date
   #oldestFetchedMessage?: FetchedMessage
@@ -81,6 +84,7 @@ export class Chat {
     this.#pinEvents = new Map()
     this.#reactEvents = new Map()
     this.#deleteEvents = new Map()
+    this.#isActive = false
     this.messageCallbacks = new Set()
   }
 
@@ -142,6 +146,7 @@ export class Chat {
     return this.#messages.get(id)
   }
 
+  // todo?: delete
   public onChange = (callback: (description: CommunityChat) => void) => {
     this.chatCallbacks.add(callback)
 
@@ -158,9 +163,16 @@ export class Chat {
     callback: (messages: ChatMessage[]) => void
   ): (() => void) => {
     this.messageCallbacks.add(callback)
+    // todo?: set from ui, think use case without an ui
+    this.#isActive = true
+    // todo?!: only if in `unreadChats`, keep "unreads" separate from `notifications`
+    // todo?: only if at the bottom and all unread messages are in view
+    // todo?: call from ui
+    this.client.activityCenter.removeChatNotifications(this.uuid)
 
     return () => {
       this.messageCallbacks.delete(callback)
+      this.#isActive = false
     }
   }
 
@@ -305,6 +317,11 @@ export class Chat {
 
     // callback
     this.emitMessages()
+
+    // todo?: if not muted
+    if (!this.#isActive) {
+      this.client.activityCenter.addMessageNotifications(newMessage)
+    }
   }
 
   public handleEditedMessage = (
diff --git a/packages/status-js/src/client/client.ts b/packages/status-js/src/client/client.ts
index 97d53d03..45e6a3c8 100644
--- a/packages/status-js/src/client/client.ts
+++ b/packages/status-js/src/client/client.ts
@@ -12,6 +12,7 @@ import {
 
 import { ApplicationMetadataMessage } from '../protos/application-metadata-message'
 import { Account } from './account'
+import { ActivityCenter } from './activityCenter'
 import { Community } from './community/community'
 import { handleWakuMessage } from './community/handle-waku-message'
 
@@ -37,6 +38,7 @@ class Client {
    */
   #wakuDisconnectionTimer: ReturnType<typeof setInterval>
 
+  public activityCenter: ActivityCenter
   public account?: Account
   public community: Community
 
@@ -50,6 +52,9 @@ class Client {
     this.wakuMessages = new Set()
     this.#wakuDisconnectionTimer = wakuDisconnectionTimer
 
+    // Activity Center
+    this.activityCenter = new ActivityCenter(/* this */)
+
     // Community
     this.community = new Community(this, options.publicKey)
   }
diff --git a/packages/status-js/src/client/community/community.ts b/packages/status-js/src/client/community/community.ts
index 40c5426e..c2bee8c2 100644
--- a/packages/status-js/src/client/community/community.ts
+++ b/packages/status-js/src/client/community/community.ts
@@ -267,6 +267,9 @@ export class Community {
       this.contentTopic,
       this.symmetricKey
     )
+
+    // todo?:
+    // this.client.activityCenter.addJoiningRequestNotification(...)
   }
 
   public isOwner = (