curl --request POST \
  --url https://api.example.com/v1/usage-billing/subscriptions \
  --header 'Content-Type: application/json' \
  --header 'Idempotency-Key: <idempotency-key>' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "customerRef": "<string>",
  "overageLimit": "<string>",
  "planId": "<string>"
}
'

import requests

url = "https://api.example.com/v1/usage-billing/subscriptions"

payload = {
    "customerRef": "<string>",
    "overageLimit": "<string>",
    "planId": "<string>"
}
headers = {
    "Idempotency-Key": "<idempotency-key>",
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'Idempotency-Key': '<idempotency-key>',
    'x-api-key': '<api-key>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({customerRef: '<string>', overageLimit: '<string>', planId: '<string>'})
};

fetch('https://api.example.com/v1/usage-billing/subscriptions', 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.example.com/v1/usage-billing/subscriptions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'customerRef' => '<string>',
    'overageLimit' => '<string>',
    'planId' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "Idempotency-Key: <idempotency-key>",
    "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"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.example.com/v1/usage-billing/subscriptions"

	payload := strings.NewReader("{\n  \"customerRef\": \"<string>\",\n  \"overageLimit\": \"<string>\",\n  \"planId\": \"<string>\"\n}")

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

	req.Header.Add("Idempotency-Key", "<idempotency-key>")
	req.Header.Add("x-api-key", "<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))

}

HttpResponse<String> response = Unirest.post("https://api.example.com/v1/usage-billing/subscriptions")
  .header("Idempotency-Key", "<idempotency-key>")
  .header("x-api-key", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"customerRef\": \"<string>\",\n  \"overageLimit\": \"<string>\",\n  \"planId\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.example.com/v1/usage-billing/subscriptions")

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

request = Net::HTTP::Post.new(url)
request["Idempotency-Key"] = '<idempotency-key>'
request["x-api-key"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"customerRef\": \"<string>\",\n  \"overageLimit\": \"<string>\",\n  \"planId\": \"<string>\"\n}"

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

{
  "data": {
    "autoRenewEnabled": false,
    "cancelAtPeriodEnd": false,
    "createdAt": "2026-10-13T12:00:00.000Z",
    "currency": "EUR",
    "customerRef": "customer_123",
    "id": "22222222-2222-4222-8222-222222222222",
    "includedCredits": "1000",
    "monthlyPrice": "20.00",
    "notificationEmailConfigured": false,
    "notificationEnabled": false,
    "notificationLocale": "en",
    "overageAmount": "0.00",
    "overageCredits": "0",
    "overageLimit": "10.00",
    "overageUnitPrice": "0.01",
    "paymentState": "pay_by_link",
    "periodEnd": null,
    "periodStart": null,
    "planId": "11111111-1111-4111-8111-111111111111",
    "planName": "Starter",
    "remainingCredits": "0",
    "status": "pending_payment",
    "unit": "request",
    "usedCredits": "0"
  }
}

{
  "errorCode": "USAGE_INPUT_INVALID",
  "message": "USAGE_INPUT_INVALID",
  "statusCode": 400
}

{
  "error": "Unauthorized",
  "message": "Invalid API key",
  "statusCode": 401
}

{
  "errorCode": "USAGE_SCOPE_INACTIVE",
  "statusCode": 403
}

{
  "errorCode": "USAGE_SUBSCRIPTION_NOT_FOUND",
  "statusCode": 404
}

{
  "errorCode": "USAGE_EVENT_CONFLICT",
  "statusCode": 409
}

{
  "errorCode": "IDEMPOTENCY_KEY_REUSED",
  "statusCode": 422
}

{
  "error": "RATE_LIMITED",
  "errorCode": "RATE_LIMITED",
  "message": "Too many requests. Retry after the indicated delay.",
  "status": false,
  "statusCode": 429
}

{
  "errorCode": "UPSTREAM_UNAVAILABLE",
  "statusCode": 502
}

{
  "error": "Service Unavailable",
  "message": "API_KEY_VALIDATION_UNAVAILABLE",
  "statusCode": 503
}

{
  "errorCode": "UPSTREAM_TIMEOUT",
  "statusCode": 504
}