Can I use the same number on the WhatsApp app and the API?

Yes, through coexistence: your provider onboards your Business app number to the API, and the app keeps working. Without it, a number can't be on both, and moving means deleting the account first.

• Coexistence needs a provider that is a Solution Partner or Tech Provider, and Business app version 2.24.17 or higher.
• You can still chat one to one in the app. WhatsApp keeps both in sync, and the last 6 months of chats can sync.
• Messages you send in the app stay free. Messages sent through the API are charged at Meta's rates.
• Trade-offs: broadcast lists become read-only, linked devices are unlinked when you onboard, and API throughput is fixed at 20 messages per second.
• Without coexistence, you must delete the Business app account before the number can join the API, and you lose its chat history.