Is the WhatsApp order summary a GST invoice?

No. WhatsApp says the order summary is not a substitute for an invoice, cash memo, bill or receipt. You stay responsible for issuing the tax invoice your law requires.

• The summary lists the goods, price per item, total and payment details in the chat. It does not count as a tax document.
• WhatsApp says businesses are solely responsible for issuing an invoice or other statutory document required by law.
• What a GST invoice must show depends on your registration, so ask your accountant. Issue it from your billing software or POS.
• In India, the Business app asks for your legal name, business type, licence or registration, customer care and grievance officer details.