curl --request POST \
  --url https://api.kraken.com/0/private/CheckOtcClient \
  --header 'API-Key: <api-key>' \
  --header 'API-Sign: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "nonce": 123
}'

import requests

url = "https://api.kraken.com/0/private/CheckOtcClient"

payload = { "nonce": 123 }
headers = {
    "API-Key": "<api-key>",
    "API-Sign": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'API-Key': '<api-key>',
    'API-Sign': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({nonce: 123})
};

fetch('https://api.kraken.com/0/private/CheckOtcClient', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.kraken.com/0/private/CheckOtcClient"

	payload := strings.NewReader("{\n  \"nonce\": 123\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("API-Key", "<api-key>")
	req.Header.Add("API-Sign", "<api-key>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

{
  "error": [
    "EGeneral:Invalid arguments"
  ],
  "result": {
    "permissions": [
      "<string>"
    ]
  }
}

{
  "errors": [
    {
      "field": null,
      "value": null,
      "type": "Internal Error",
      "msg": "Internal error",
      "severity": "E",
      "errorClass": "General"
    }
  ]
}