What is chatId?

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@c.us

• Format: [phoneNumber]@c.us
• Use this when you know the contact’s phone number.
• This is the standard phone-number-based identifier for direct messaging.
• Do not include +, spaces, or punctuation in the numeric part.
• Example: [email protected]

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@lid

• Format: [numericIdentifier]@lid
• Use this when the contact is represented by a linked identifier instead of a visible phone number.
• This is a privacy-preserving identifier. The same person can have both an @lid value and an @c.us value.
• Example: 1111111@lid

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Difference Between @c.us And @lid

• @c.us is based on the phone number.
• @lid is based on a linked identifier.
• Both can refer to the same contact.
• The contact conversion endpoints let you map one format to the other when the mapping is already known by your instance.

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Formatting Rules

• Keep the numeric part clean. Do not send +, spaces, or punctuation in phone-number-based values.
• When an endpoint accepts the identifier inside the URL path, encode @ as %40.
• For example, use 1111111%40lid or 201553730661%40c.us in path-based endpoints.
• Some conversion endpoints also accept only the numeric part, such as 1111111 or 201553730661.

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When To Convert

• Resolve a linked identifier to a phone-number chat ID.
• Resolve a phone-number chat ID to a linked identifier.
• List or count the mappings your instance already knows.