{
  "operation": "POST /api/v1/app/{app_id}/msg",
  "summary": "Send Message",
  "description": "Send a webhook message. Svix fans it out to every endpoint subscribed to the eventType, signs it with each endpoint's secret, and handles retries on failure.",
  "request": {
    "method": "POST",
    "url": "https://api.us.svix.com/api/v1/app/app_1srOrx2ZWZBpBUvZwXKQmoEYga2/msg",
    "headers": {
      "Authorization": "Bearer testsk_xxxxxxxxxxxxxxxxxxxxxxxxxx",
      "Content-Type": "application/json",
      "Idempotency-Key": "9bf08ec8-1234-4abc-9def-0123456789ab"
    },
    "body": {
      "eventType": "invoice.paid",
      "eventId": "evt_inv_20260522_001",
      "payload": {
        "invoiceId": "inv_98765",
        "userId": "user_42",
        "amountCents": 4900,
        "currency": "USD",
        "paidAt": "2026-05-22T15:32:11Z"
      },
      "channels": [
        "project_123"
      ],
      "tags": [
        "billing",
        "production"
      ],
      "payloadRetentionPeriod": 90
    }
  },
  "response": {
    "status": 202,
    "body": {
      "id": "msg_3srOrx2ZWZBpBUvZwXKQmoEYga2",
      "eventId": "evt_inv_20260522_001",
      "eventType": "invoice.paid",
      "payload": {
        "invoiceId": "inv_98765",
        "userId": "user_42",
        "amountCents": 4900,
        "currency": "USD",
        "paidAt": "2026-05-22T15:32:11Z"
      },
      "channels": [
        "project_123"
      ],
      "tags": [
        "billing",
        "production"
      ],
      "timestamp": "2026-05-22T15:32:11Z"
    }
  }
}