sendVoice

This page describes the sendVoice() function in zalo-bot-js, used to send a voice message (.aac audio file) to a user in a 1-on-1 chat.

⚠️ Limitation: This API only supports sending voice messages to 1-on-1 chats. It does not support groups. If you pass a group chat_id, the request may appear successful but the message will not be delivered.

Function signature

sendVoice(
  chatId: string,
  voiceUrl: string,
  options?: SendVoiceOptions,
): Promise<Message>

When to use it

• send an audio/voice message to a user
• reply with an audio file from your server
• deliver voice content in a 1-on-1 conversation

Parameters

Parameter	Type	Required	Description
chatId	string	Yes	ID of the recipient (1-on-1 only)
voiceUrl	string	Yes	URL to the audio file (must be .aac format)
options.reply_to_message_id	string	No	Message ID to reply to
options.requestOptions	RequestOptions	No	Advanced request options

Format requirements

• File format: .aac audio only
• No caption or text attached to voice messages
• URL must be publicly accessible

Return value

Returns Promise<Message>.

Example

import { Bot } from "zalo-bot-js";

const bot = new Bot({ token: process.env.ZALO_BOT_TOKEN! });

await bot.sendVoice("user-chat-id", "https://example.com/audio.aac");

Example with reply

bot.on("text", async (message) => {
  await bot.sendVoice(
    message.chat.id,
    "https://example.com/response.aac",
    {
      reply_to_message_id: message.messageId,
    },
  );
});

Practical notes

• sendVoice() only works in 1-on-1 chats
• passing a group chat_id may return success but the message won't be delivered
• the audio file must be in .aac format
• the voice_url must be a valid, publicly accessible HTTPS URL

Next

• See sendMessage for text messages.
• See sendPhoto for image messages.
• See sendSticker for sticker messages.

Last updated: September 7, 2026