Send a message

The request#

curl -X POST https://sendrixbackend.exebee.com/v1/messages \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: order-4471-shipped" \
  -d '{
    "to": "919833663235",
    "template": {
      "name": "order_shipped",
      "language": "en",
      "variables": { "1": "Asha", "2": "BK-4471" }
    }
  }'

HTTP/1.1 202 Accepted

{
  "id": "msg_c16cead6-8385-481f-9e2e-e146d51f2738",
  "object": "message",
  "to": "919833663235",
  "status": "queued",
  "template_id": "tpl_cb9182c4-6e22-4095-bd26-a61c9f8d7fba",
  "wa_message_id": null,
  "error": null,
  "created_at": "2026-08-28T15:03:25.424Z",
  "sent_at": null, "delivered_at": null, "read_at": null, "failed_at": null
}

Requires messages:send. A 202means we have taken it and accounted for it: one credit, or one message off your plan’s allowance. It does not mean WhatsApp has it yet.

Sending a file#

There are two ways, and which one you need depends entirely on whether the person has messaged you recently.

On a template, to anybody

A template whose header is an image, video or document carries the file with it, and a template reaches anybody. This is what an order confirmation with the product photo, or a shipping note with the label attached, actually is.

curl -X POST https://sendrixbackend.exebee.com/v1/messages \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: order-4471-invoice" \
  -d '{
    "to": "919833663235",
    "template": {
      "name": "order_invoice",
      "variables": { "1": "Asha", "2": "BK-4471" },
      "header_media": {
        "link": "https://yourshop.example/invoices/4471.pdf",
        "filename": "invoice-4471.pdf"
      }
    }
  }'

requires_media_header on the template listing tells you which of your templates need this. Send one without it and you get 400 header_media_required rather than a message that fails at WhatsApp after we have already accepted it.

On its own, inside the 24 hour window

A bare file, with no template around it. It only reaches somebody who has messaged you in the last 24 hours. That is WhatsApp’s rule, not ours, and it makes this a reply, not a way to start a conversation.

curl -X POST https://sendrixbackend.exebee.com/v1/messages \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "to": "919833663235",
    "media": {
      "type": "image",
      "link": "https://yourshop.example/receipts/4471.jpg",
      "caption": "Your receipt"
    }
  }'

A bare file costs nothing. WhatsApp stopped charging for service messages in July 2025, so this is free, exactly like the same attachment sent from your inbox. A template always costs a credit, media header or not.

Templates with a WhatsApp Flow#

A template can carry a WhatsApp Flowbutton: a form that opens inside WhatsApp, for a booking, a lead, a photo upload. These send like any other template. The button’s one parameter, a flow_token, is filled in for you, and flow_buttons on the template tells you a template has one.

Pass template.flowwhen you want to choose that token, or fill the form’s first screen:

curl -X POST https://sendrixbackend.exebee.com/v1/messages \
  -H "Authorization: Bearer sk_live_..." \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: lead-8812-form" \
  -d '{
    "to": "919833663235",
    "template": {
      "name": "book_a_visit",
      "flow": {
        "token": "lead-8812",
        "data": { "name": "Asha", "city": "Pune" }
      }
    }
  }'

When somebody submits the form you get a flow.completed webhook, and the answers are readable at Form submissions. Passing template.flow to a template with no flow button is refused with 400 flow_not_on_template.

Why it does not wait#

Sending inline would mean your checkout holding a connection open across a call to Meta that can take thirty seconds, with nothing to retry it when that fails. Queuing means your message gets the same retries, pacing and rate-limit backoff that campaigns get, and your request comes back in milliseconds.

In practice it leaves for Meta well under a second later. You learn the outcome from webhooks, or by reading the message back.

Fields#

Retrying safely#

Send an Idempotency-Key header on every send. It is the difference between a timeout costing you nothing and a customer getting two one-time codes.

• Same key, same body: you get the original response back, with an Idempotent-Replay: true header. Nothing is sent twice and nothing is charged twice.
• Same key, different body: 409 idempotency_key_reused. Your key is not as unique as your code thinks.
• Same key while the first is still running: 409 idempotency_in_progress. Retry in a moment.

Keys are remembered for 24 hours and are scoped to your workspace. Use something naturally unique to the event, like order-4471-shipped, rather than a random value your retry cannot reproduce.

Reading a message back#

curl https://sendrixbackend.exebee.com/v1/messages/msg_c16cead6-8385-481f-9e2e-e146d51f2738 \
  -H "Authorization: Bearer sk_live_..."

Requires messages:read. Useful while you are building, before your webhook exists. Once it does, prefer the webhook: polling every message costs you rate limit for information we would have pushed.

A message that carried a WhatsApp Flow also lists the forms submitted from it, as flow_responses: ids and times. Read the answers with GET /v1/flow_responses/{id}.

Statuses

Treat this list as able to grow. A status you do not recognise should be handled as “still in flight” rather than crashing.

What a send costs#

On credits: one, reserved when we accept the message and settled when Meta says what happened. A message that never arrives has its credit returned automatically, the same as a campaign send. If your balance cannot cover it you get 402 insufficient_credits and nothing is queued.

On the all-inclusive plan: nothing is charged, and the send comes off the plan’s allowance for the period instead. Credits are never used, so once the allowance is gone you get 402 plan_allowance_used_up rather than a fallback to the balance.

With no plan at all: 402 plan_required. Reads keep working, so an integration can still list its senders and templates and work out what happened. See Plans and credits.