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chatId is the destination identifier used by Hypersender WhatsApp endpoints. The two formats you will work with most often are @c.us and @lid.

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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

Use the contact conversion endpoints when you need to:
  • 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.