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POST
/
v2
/
notify
/
reply
import Prelude from "@prelude.so/sdk";

const client = new Prelude();

async function main() {
  const response = await client.notify.reply({
    to: "+33612345678",
    text: "Thanks for reaching out! We'll look into your request.",
    reply_to: "im_01k8aq2zggeyssvt53zgvpx63a",
  });

  console.log(response.id);
}

main();

{
  "id": "<string>",
  "to": "<string>",
  "text": "<string>",
  "reply_to": "<string>",
  "created_at": "2023-11-07T05:31:56Z",
  "callback_url": "<string>",
  "correlation_id": "<string>"
}
import Prelude from "@prelude.so/sdk";

const client = new Prelude();

async function main() {
  const response = await client.notify.reply({
    to: "+33612345678",
    text: "Thanks for reaching out! We'll look into your request.",
    reply_to: "im_01k8aq2zggeyssvt53zgvpx63a",
  });

  console.log(response.id);
}

main();
Replies are delivered as native WhatsApp quoted messages and must be sent within the 24-hour conversation window that follows the latest inbound message from the same user. See WhatsApp 2-Way Messaging for the full flow.

​
Request fields

​
to
string
required
The recipient’s phone number in E.164 format. Must match the phone number that sent the original inbound message — otherwise a phone_number_mismatch error is returned.
​
text
string
required
The reply message body. Sent as a free-form WhatsApp text, not as a template.
​
reply_to
string
required
The inbound message ID (prefixed with im_) to reply to. This ID is provided in the inbound.message.received webhook event.
​
callback_url
string
The URL where webhooks will be sent for delivery events of this reply.
​
correlation_id
string
A user-defined identifier to correlate this reply with your internal systems. It is returned in the response and any webhook events that refer to this message.

​
Error Handling

The reply endpoint returns specific error codes for 2-way messaging failures:
Error CodeDescriptionAction
window_expiredThe 24-hour WhatsApp conversation window has closedUse a template-based message via Send a message instead
invalid_reply_contextThe inbound message ID in reply_to was not foundVerify the message ID from the inbound.message.received webhook
phone_number_mismatchThe to number does not match the inbound message senderUse the phone number from the inbound webhook
missing_textThe text field is emptyProvide a reply message body
invalid_phone_numberPhone number format is invalidValidate phone number format
insufficient_balanceAccount balance is too lowTop up your account
For a complete list of errors, see the Error documentation.

Authorizations

​
Authorization
string
header
required

Bearer authentication header of the form Bearer <token>, where <token> is your auth token.

Body

application/json
​
to
string
required

The recipient's phone number in E.164 format. Must match the phone number that sent the original inbound message.

Example:

"+33612345678"

​
text
string
required

The reply message body sent as a free-form WhatsApp text.

Example:

"Thanks for reaching out! We'll look into your request."

​
reply_to
string
required

The inbound message ID (prefixed with im_) to reply to. This ID is provided in the inbound.message.received webhook event.

Example:

"im_01k8aq2zggeyssvt53zgvpx63a"

​
callback_url
string

The URL where webhooks will be sent for delivery events of this reply.

Example:

"https://your-app.com/webhooks/notify"

​
correlation_id
string

A user-defined identifier to correlate this reply with your internal systems. It is returned in the response and any webhook events that refer to this message.

Maximum string length: 80
Example:

"support-ticket-42"

Callbacks

POST
{$request.body#/callback_url}webhook_event

Body

application/json
​
id
string
required

The event identifier.

Example:

"evt_01hynf45qvevj844m9az2x2f3c"

​
created_at
string<date-time>
required

The event creation date.

Example:

"2028-01-01T00:00:00Z"

​
type
string
required

The event type.

Example:

"<message_type>"

​
payload
object
required

The event payload.

Response

Your server accepted the event and will process it.

Response

OK

​
id
string
required

The reply message identifier.

Example:

"tx_01k8ap1btqf5r9fq2c8ax5fhc9"

​
to
string
required

The recipient's phone number in E.164 format.

Example:

"+33612345678"

​
text
string
required

The reply message body that was sent.

Example:

"Thanks for reaching out! We'll look into your request."

​
reply_to
string
required

The inbound message ID this reply was sent in response to.

Example:

"im_01k8aq2zggeyssvt53zgvpx63a"

​
created_at
string<date-time>
required

The reply creation date in RFC3339 format.

Example:

"2025-10-24T12:00:00Z"

​
callback_url
string

The callback URL where webhooks will be sent.

Example:

"https://your-app.com/webhooks/notify"

​
correlation_id
string

The user-defined correlation identifier echoed back from the request.

Maximum string length: 80
Example:

"support-ticket-42"