Understanding Chat IDs

Every conversation in WhatsApp — whether with an individual, a group, or a broadcast list — is identified by a chat ID. You will use chat IDs in every message operation.

Format

A chat ID follows this pattern:

identifier@suffix

The suffix determines the type of conversation.

Suffix Types

@c.us — Individual Contacts

This is the most common suffix. It represents a direct conversation with a single contact. The identifier is the phone number in international format without the + sign.

1234567890@c.us    ← Phone number 1234567890
447700900000@c.us  ← UK number +44 7700 900000

@g.us — Group Chats

Group IDs are assigned by WhatsApp when a group is created. They contain a numeric identifier followed by a timestamp-like suffix.

1234567890-1234567890@g.us

You cannot construct a group ID from a phone number. You must obtain it from:

• An incoming group message (check message.from or message.chatId)
• The API (listing groups)
• An invite link (see below)

@lid — Linked Device IDs

LIDs are used for linked devices and certain internal WhatsApp identifiers. They use a colon-separated format. Most ordinary automation tasks will not need LIDs.

@broadcast — Broadcast Lists

The status broadcast list uses a fixed identifier:

status@broadcast

Converting Phone Numbers to Chat IDs

To convert a phone number to a chat ID:

1. Start with international format — Include the country code (e.g., +44 for UK, +1 for US)
2. Remove the + sign — +447700900000 becomes 447700900000
3. Remove spaces, dashes, and parentheses — +1 (555) 123-4567 becomes 15551234567
4. Append @c.us — 15551234567@c.us

function phoneToChatId(phone: string): string {
  // Remove +, spaces, dashes, parentheses
  const cleaned = phone.replace(/[\+\-\s\(\)]/g, '');
  return `${cleaned}@c.us`;
}

phoneToChatId('+44 7700 900000'); // '447700900000@c.us'
phoneToChatId('+1 (555) 123-4567'); // '15551234567@c.us'

Getting Group IDs

From Messages

When you receive a message from a group, the message.from or message.chatId field contains the group ID:

client.onMessage((message) => {
  if (message.isGroupMsg) {
    console.log('Group ID:', message.from); // '1234567890-1234567890@g.us'
  }
});

From Invite Links

Group invite links contain the group ID in the URL:

https://chat.whatsapp.com/ABCdefGHIjklMNOpqrSTUv

You can use the API to resolve an invite link to a group ID.

Common Mistakes

Related

• Messages guide — Send and receive messages using chat IDs
• Groups guide — Working with group chats

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