curl --request GET \
  --url https://api.otark.energy/v1/customers \
  --header 'X-Api-Key: <api-key>'

import requests

url = "https://api.otark.energy/v1/customers"

headers = {"X-Api-Key": "<api-key>"}

response = requests.get(url, headers=headers)

print(response.text)

const options = {method: 'GET', headers: {'X-Api-Key': '<api-key>'}};

fetch('https://api.otark.energy/v1/customers', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.otark.energy/v1/customers",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "X-Api-Key: <api-key>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api.otark.energy/v1/customers"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("X-Api-Key", "<api-key>")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.get("https://api.otark.energy/v1/customers")
  .header("X-Api-Key", "<api-key>")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.otark.energy/v1/customers")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Get.new(url)
request["X-Api-Key"] = '<api-key>'

response = http.request(request)
puts response.read_body

{
  "customers": [
    {
      "id": "cust_r8s9t0u1",
      "name": "SolarDach GmbH",
      "status": "active",
      "balance_group": {
        "eic": "11YSOLARDACH--A",
        "tso": "DE_AMPRION"
      },
      "metadata": {
        "customer_number": "KD-2026-0815",
        "cost_center": "CC-4200",
        "region": "NRW"
      },
      "assigned_at": "2026-01-10T09:00:00Z",
      "created_at": "2026-01-10T09:00:00Z",
      "activated_at": "2026-01-10T11:30:00Z"
    }
  ],
  "pagination": {
    "limit": 10,
    "has_more": true,
    "next_cursor": "txn_k8m2p4q7r1"
  }
}

{
  "type": "https://brp.otark.team/errors/validation",
  "title": "Validation Failed",
  "status": 400,
  "instance": "/v1/customers/cust_r8s9t0u1",
  "errors": [
    {
      "field": "balance_group.tso",
      "code": "invalid_enum_value",
      "message": "Invalid enum value. Expected 'DE_AMPRION' | 'DE_TENNET' | 'DE_TRANSNET_BW' | 'DE_50HERTZ', received 'INVALID'"
    }
  ]
}

{
  "type": "https://brp.otark.team/errors/invalid_api_key",
  "title": "Invalid API Key",
  "status": 401
}

{
  "type": "https://brp.otark.team/errors/insufficient_scopes",
  "title": "Insufficient API Key Scopes",
  "status": 403,
  "detail": "Missing scope: customers:write. Please create a new API key with the required scopes."
}