curl --request POST \
  --url https://api.centralcart.io/v1/webstore/cart \
  --header 'Content-Type: application/json' \
  --header 'x-store-domain: <x-store-domain>' \
  --data '
{
  "items": [
    {
      "id": 1,
      "quantity": 2
    },
    {
      "id": 7,
      "quantity": 1,
      "is_upsell": true,
      "upsell_trigger_id": 1
    }
  ]
}
'

import requests

url = "https://api.centralcart.io/v1/webstore/cart"

payload = { "items": [
        {
            "id": 1,
            "quantity": 2
        },
        {
            "id": 7,
            "quantity": 1,
            "is_upsell": True,
            "upsell_trigger_id": 1
        }
    ] }
headers = {
    "x-store-domain": "<x-store-domain>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'x-store-domain': '<x-store-domain>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    items: [
      {id: 1, quantity: 2},
      {id: 7, quantity: 1, is_upsell: true, upsell_trigger_id: 1}
    ]
  })
};

fetch('https://api.centralcart.io/v1/webstore/cart', 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.centralcart.io/v1/webstore/cart",
  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([
    'items' => [
        [
                'id' => 1,
                'quantity' => 2
        ],
        [
                'id' => 7,
                'quantity' => 1,
                'is_upsell' => true,
                'upsell_trigger_id' => 1
        ]
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "x-store-domain: <x-store-domain>"
  ],
]);

$response = curl_exec($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.centralcart.io/v1/webstore/cart"

	payload := strings.NewReader("{\n  \"items\": [\n    {\n      \"id\": 1,\n      \"quantity\": 2\n    },\n    {\n      \"id\": 7,\n      \"quantity\": 1,\n      \"is_upsell\": true,\n      \"upsell_trigger_id\": 1\n    }\n  ]\n}")

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

	req.Header.Add("x-store-domain", "<x-store-domain>")
	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.centralcart.io/v1/webstore/cart")
  .header("x-store-domain", "<x-store-domain>")
  .header("Content-Type", "application/json")
  .body("{\n  \"items\": [\n    {\n      \"id\": 1,\n      \"quantity\": 2\n    },\n    {\n      \"id\": 7,\n      \"quantity\": 1,\n      \"is_upsell\": true,\n      \"upsell_trigger_id\": 1\n    }\n  ]\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.centralcart.io/v1/webstore/cart")

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

request = Net::HTTP::Post.new(url)
request["x-store-domain"] = '<x-store-domain>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"items\": [\n    {\n      \"id\": 1,\n      \"quantity\": 2\n    },\n    {\n      \"id\": 7,\n      \"quantity\": 1,\n      \"is_upsell\": true,\n      \"upsell_trigger_id\": 1\n    }\n  ]\n}"

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

[
  {
    "id": 1,
    "name": "VIP Inicial",
    "slug": "vip-inicial",
    "pricing": {
      "price": 10,
      "compare_at": 20,
      "percent_discount": -50
    },
    "stock": {
      "quantity": 100,
      "available": true,
      "min_amount": 1
    }
  },
  {
    "id": 7,
    "name": "Chave Bônus",
    "slug": "chave-bonus",
    "is_upsell": true,
    "upsell_trigger_id": 1,
    "pricing": {
      "price": 5,
      "compare_at": 15,
      "percent_discount": -66.67
    },
    "stock": {
      "quantity": null,
      "available": true,
      "min_amount": 1
    }
  }
]

{
  "errors": [
    {
      "message": "Store not found."
    }
  ]
}