curl --request POST \
  --url https://api.fintoc.com/v2/subscriptions/{subscription_id}/items \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "price_data": {
    "currency": "CLP",
    "recurring": {
      "interval": "month",
      "interval_count": 1
    },
    "unit_amount": 5000,
    "product_data": {
      "name": "Extra seat"
    }
  },
  "quantity": 2
}
'

import requests

url = "https://api.fintoc.com/v2/subscriptions/{subscription_id}/items"

payload = {
    "price_data": {
        "currency": "CLP",
        "recurring": {
            "interval": "month",
            "interval_count": 1
        },
        "unit_amount": 5000,
        "product_data": { "name": "Extra seat" }
    },
    "quantity": 2
}
headers = {
    "Authorization": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    price_data: {
      currency: 'CLP',
      recurring: {interval: 'month', interval_count: 1},
      unit_amount: 5000,
      product_data: {name: 'Extra seat'}
    },
    quantity: 2
  })
};

fetch('https://api.fintoc.com/v2/subscriptions/{subscription_id}/items', 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.fintoc.com/v2/subscriptions/{subscription_id}/items",
  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([
    'price_data' => [
        'currency' => 'CLP',
        'recurring' => [
                'interval' => 'month',
                'interval_count' => 1
        ],
        'unit_amount' => 5000,
        'product_data' => [
                'name' => 'Extra seat'
        ]
    ],
    'quantity' => 2
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: <api-key>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($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.fintoc.com/v2/subscriptions/{subscription_id}/items"

	payload := strings.NewReader("{\n  \"price_data\": {\n    \"currency\": \"CLP\",\n    \"recurring\": {\n      \"interval\": \"month\",\n      \"interval_count\": 1\n    },\n    \"unit_amount\": 5000,\n    \"product_data\": {\n      \"name\": \"Extra seat\"\n    }\n  },\n  \"quantity\": 2\n}")

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

	req.Header.Add("Authorization", "<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.fintoc.com/v2/subscriptions/{subscription_id}/items")
  .header("Authorization", "<api-key>")
  .header("Content-Type", "application/json")
  .body("{\n  \"price_data\": {\n    \"currency\": \"CLP\",\n    \"recurring\": {\n      \"interval\": \"month\",\n      \"interval_count\": 1\n    },\n    \"unit_amount\": 5000,\n    \"product_data\": {\n      \"name\": \"Extra seat\"\n    }\n  },\n  \"quantity\": 2\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.fintoc.com/v2/subscriptions/{subscription_id}/items")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = '<api-key>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"price_data\": {\n    \"currency\": \"CLP\",\n    \"recurring\": {\n      \"interval\": \"month\",\n      \"interval_count\": 1\n    },\n    \"unit_amount\": 5000,\n    \"product_data\": {\n      \"name\": \"Extra seat\"\n    }\n  },\n  \"quantity\": 2\n}"

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

{
  "id": "si_2c4mDfkPLLrLTCJ3wPCEHGYpkVf",
  "object": "subscription_item",
  "price": {
    "currency": "CLP",
    "product": {
      "id": "prod_2c4mDgwQqkNwMHnXSc4DBjkbcWz",
      "object": "product",
      "created_at": "2026-06-01T15:00:00Z",
      "description": null,
      "image_url": null,
      "metadata": {},
      "mode": "live",
      "name": "Extra seat"
    },
    "recurring": {
      "interval": "month",
      "interval_count": 1
    },
    "unit_amount": 5000
  },
  "quantity": 2
}

{
  "error": {
    "type": "invalid_request_error",
    "code": "missing_parameter",
    "param": "price_data",
    "message": "Missing required param: price_data",
    "doc_url": "https://docs.fintoc.com/reference/errors"
  }
}

{
  "error": {
    "type": "authentication_error",
    "code": "invalid_api_key",
    "message": "Invalid API Key: invalid-*oken"
  }
}

{
  "error": {
    "type": "invalid_request_error",
    "code": "missing_resource",
    "param": "subscription_id",
    "message": "No such invoicing/subscription: sub_2c4mDcMaVxDx7nT3o5GbPMQbS2v",
    "doc_url": "https://docs.fintoc.com/reference/errors"
  }
}

{
  "error": {
    "type": "invalid_request_error",
    "code": "currency_mismatch",
    "message": "Each subscription item's price currency must be compatible with the subscription's billing currency"
  }
}