Message broadcast

Last updated Oct 19, 2026 The broadcast APIs allow a user to send custom messages to all other users in a meeting.

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Broadcasting a Message

The Participants module on the meeting object allows you to broadcast messages to all other users in a meeting (or to other meetings in case of connected meetings) over the signaling channel.

• If target is omitted, the message is broadcast to all participants in the current meeting, including the local participant.
• If target.participantIds is provided, the message is sent only to those participants in the current meeting.
• If target.presetNames is provided, the message is sent to all participants whose preset name is in the list.
• If target.meetingIds is provided, the message is broadcast to all specified meetings (multi‑meeting broadcast).

const participants = useRealtimeKitSelector((m) => m.participants);
participants.broadcastMessage(
  type: Exclude<string, 'spotlight'>,
  payload: BroadcastMessagePayload,
  target?: BroadcastMessageTarget,
): Promise<void>

type BroadcastMessagePayload = {
    [key: string]: boolean | number | string | Date | ActiveTab;
};

type BroadcastMessageTarget =
    | { participantIds: string[] }
    | { presetNames: string[] }
    | { meetingIds: string[] };

• If target is omitted, the message is broadcast to all participants in the current meeting, including the local participant.
• If target.participantIds is provided, the message is sent only to those participants in the current meeting.
• If target.presetNames is provided, the message is sent to all participants whose preset name is in the list.
• If target.meetingIds is provided, the message is broadcast to all specified meetings (multi‑meeting broadcast).

meeting.participants.broadcastMessage(
  type: Exclude<string, 'spotlight'>,
  payload: BroadcastMessagePayload,
  target?: BroadcastMessageTarget,
): Promise<void>

type BroadcastMessagePayload = {
    [key: string]: boolean | number | string | Date | ActiveTab;
};

type BroadcastMessageTarget =
    | { participantIds: string[] }
    | { presetNames: string[] }
    | { meetingIds: string[] };

• If target is omitted, the message is broadcast to all participants in the current meeting, including the local participant.
• If target.participantIds is provided, the message is sent only to those participants in the current meeting.
• If target.presetNames is provided, the message is sent to all participants whose preset name is in the list.
• If target.meetingIds is provided, the message is broadcast to all specified meetings (multi‑meeting broadcast).

meeting.participants.broadcastMessage(
  type: Exclude<string, 'spotlight'>,
  payload: BroadcastMessagePayload,
  target?: BroadcastMessageTarget,
): Promise<void>

type BroadcastMessagePayload = {
    [key: string]: boolean | number | string | Date | ActiveTab;
};

type BroadcastMessageTarget =
    | { participantIds: string[] }
    | { presetNames: string[] }
    | { meetingIds: string[] };

Subscribe to Messages

Use the broadcastedMessage event to listen for messages sent via broadcastMessage and handle them in your application.

const participants = useRealtimeKitSelector((m) => m.participants);
participants.on("broadcastedMessage", ({ type, payload, timestamp }) => {
    // handle message
});

meeting.participants.on(
    "broadcastedMessage",
    ({ type, payload, timestamp }) => {
        // handle message
    },
);

meeting.participants.on(
    "broadcastedMessage",
    ({ type, payload, timestamp }) => {
        // handle message
    },
);

Rate Limiting & Constraints

• The method is rate‑limited (server‑side + client‑side) to prevent abuse.
• Default client‑side config in the deprecated module: maxInvocations = 5 per period = 1s.
• The Participants module exposes a rateLimitConfig and updateRateLimits(maxInvocations, period) for tuning on the client, but server‑side limits may still apply.
• The event type cannot be spotlight. This is reserved for internal use by the SDK.

Examples

Broadcast to everyone in the meeting

const participants = useRealtimeKitSelector((m) => m.participants);
await participants.broadcastMessage("HAND_RAISE", {
    raised: true,
    userId: meeting.self.userId,
    sentAt: new Date(),
});

participants.on(
"broadcastedMessage",
({ type, payload, timestamp }) => {
if (type === "HAND_RAISE") {
// payload.raised, payload.userId, payload.sentAt
}
},
);

await meeting.participants.broadcastMessage("HAND_RAISE", {
    raised: true,
    userId: meeting.self.userId,
    sentAt: new Date(),
});

meeting.participants.on(
"broadcastedMessage",
({ type, payload, timestamp }) => {
if (type === "HAND_RAISE") {
// payload.raised, payload.userId, payload.sentAt
}
},
);

await meeting.participants.broadcastMessage("HAND_RAISE", {
    raised: true,
    userId: meeting.self.userId,
    sentAt: new Date(),
});

meeting.participants.on(
"broadcastedMessage",
({ type, payload, timestamp }) => {
if (type === "HAND_RAISE") {
// payload.raised, payload.userId, payload.sentAt
}
},
);

Broadcast to a specific set of participants.

Only the participants with those participantIds receive the message.

const participants = useRealtimeKitSelector((m) => m.participants);
await participants.broadcastMessage(
    "PRIVATE_NOTE",
    { message: "You are on stage in 30 seconds" },
    {
        participantIds: ["peer-id-1", "peer-id-2"],
    },
);

await meeting.participants.broadcastMessage(
    "PRIVATE_NOTE",
    { message: "You are on stage in 30 seconds" },
    {
        participantIds: ["peer-id-1", "peer-id-2"],
    },
);

await meeting.participants.broadcastMessage(
    "PRIVATE_NOTE",
    { message: "You are on stage in 30 seconds" },
    {
        participantIds: ["peer-id-1", "peer-id-2"],
    },
);

Broadcast to a preset

All participants whose preset name is speaker receive the message.

const participants = useRealtimeKitSelector((m) => m.participants);
await participants.broadcastMessage(
    "STAGE_INSTRUCTION",
    { text: "Prepare for Q&A" },
    {
        presetNames: ["speaker"],
    },
);

await meeting.participants.broadcastMessage(
    "STAGE_INSTRUCTION",
    { text: "Prepare for Q&A" },
    {
        presetNames: ["speaker"],
    },
);

await meeting.participants.broadcastMessage(
    "STAGE_INSTRUCTION",
    { text: "Prepare for Q&A" },
    {
        presetNames: ["speaker"],
    },
);

Broadcast across multiple meetings

All participants in the specified meetings receive the message.

const participants = useRealtimeKitSelector((m) => m.participants);
await participants.broadcastMessage(
    "GLOBAL_ANNOUNCEMENT",
    { text: "The event will end in 5 minutes." },
    {
        meetingIds: ["meeting-1", "meeting-2"],
    },
);

await meeting.participants.broadcastMessage(
    "GLOBAL_ANNOUNCEMENT",
    { text: "The event will end in 5 minutes." },
    {
        meetingIds: ["meeting-1", "meeting-2"],
    },
);

await meeting.participants.broadcastMessage(
    "GLOBAL_ANNOUNCEMENT",
    { text: "The event will end in 5 minutes." },
    {
        meetingIds: ["meeting-1", "meeting-2"],
    },
);

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description: Core concepts and terminology for RealtimeKit including apps, meetings, participants, and presets. title: Concepts image: https://developers.cloudflare.com/realtime/realtimekit/concepts/og.png?v=597dcee3ad916a41

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