curl --request POST \
  --url https://app.kapso.ai/api/v1/whatsapp_broadcasts/{broadcast_id}/recipients \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '{
  "recipients": [
    {
      "phone_number": "+14155550123",
      "template_parameters": [
        "John",
        "50% off"
      ]
    },
    {
      "phone_number": "+14155550124",
      "template_parameters": [
        "Jane",
        "40% off"
      ]
    }
  ]
}'

{
  "data": {
    "added": 500,
    "duplicates": 0,
    "errors": []
  }
}