curl --request POST \
  --url https://clarus-api.com/api/carrier_services \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-Clarus-Subdomain: <api-key>' \
  --data '
{
  "data": {
    "type": "carrier_services",
    "attributes": {
      "code": "RM1CLS",
      "name": "Royal Mail 1st Class",
      "carrier_id": 57,
      "is_default": true,
      "active": true
    }
  }
}
'

import requests

url = "https://clarus-api.com/api/carrier_services"

payload = { "data": {
        "type": "carrier_services",
        "attributes": {
            "code": "RM1CLS",
            "name": "Royal Mail 1st Class",
            "carrier_id": 57,
            "is_default": True,
            "active": True
        }
    } }
headers = {
    "Authorization": "Bearer <token>",
    "X-Clarus-Subdomain": "<api-key>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {
    Authorization: 'Bearer <token>',
    'X-Clarus-Subdomain': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    data: {
      type: 'carrier_services',
      attributes: {
        code: 'RM1CLS',
        name: 'Royal Mail 1st Class',
        carrier_id: 57,
        is_default: true,
        active: true
      }
    }
  })
};

fetch('https://clarus-api.com/api/carrier_services', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "id": 1,
  "code": "RM1CLS",
  "name": "Royal Mail 1st Class",
  "active": true,
  "is_default": true,
  "carrier_id": 57
}

{
  "error": "<string>"
}

{
  "errors": [
    {
      "code": 123,
      "symbol": "<string>",
      "details": "<string>",
      "source": "<string>",
      "context": {}
    }
  ]
}