What is an ACK in WhatsApp?
Definition
An ACK is an acknowledgement that a message has moved a step along its journey: accepted by the server, delivered to the recipient's device, or read by the recipient. It is what draws the one tick, two ticks and blue ticks in the app, and it arrives as a status event over the webhook.
In more depth
Every message you send passes through several states, and each transition is reported separately. The server acknowledging receipt is not the same as the phone having it, and the phone having it is not the same as a human having read it. Automations that treat a successful API response as delivery get this wrong: a 2xx from the send endpoint means the message was accepted for sending, and the real outcome arrives later on the status event keyed by the same message id. Read receipts are the least reliable signal, because a recipient can switch them off entirely, in which case you will never see the read state no matter how carefully you wait for it. There is a further wrinkle worth knowing about: one major engine library stopped sending delivery acknowledgements for incoming messages because WhatsApp was banning numbers that emitted them too eagerly, which means the ticks your own automation produces can themselves be a ban signal. Consume ACKs, do not try to manufacture them.
In the Wapito API
On the wire it is the field status:
{
"event": "messages.status",
"data": {
"id": "true_441234567890@c.us_3EB0",
"status": "delivered"
}
}On the official Cloud API
The Cloud API reports the same broad states - sent, delivered, read and failed - through its own webhook, with a failure reason attached when a message is rejected.
Wapito is an independent product. It is not affiliated with, endorsed by, sponsored by or certified by WhatsApp or Meta Platforms, Inc. WhatsApp is a trademark of Meta Platforms, Inc.
Related terms
Related
Endpoints that use it
Reference
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