Update a cart item

curl --request PATCH \
  --url https://api.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id} \
  --header 'Content-Type: application/json' \
  --data '{
  "quantity": 3
}'

import requests

url = "https://api.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id}"

payload = { "quantity": 3 }
headers = {"Content-Type": "application/json"}

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

print(response.text)

const options = {
  method: 'PATCH',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({quantity: 3})
};

fetch('https://api.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id}', 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.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PATCH",
  CURLOPT_POSTFIELDS => json_encode([
    'quantity' => 3
  ]),
  CURLOPT_HTTPHEADER => [
    "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.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id}"

	payload := strings.NewReader("{\n  \"quantity\": 3\n}")

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

	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.patch("https://api.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id}")
  .header("Content-Type", "application/json")
  .body("{\n  \"quantity\": 3\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.fluid.app/api/checkout/v2026-04/carts/{cart_token}/items/{id}")

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

request = Net::HTTP::Patch.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"quantity\": 3\n}"

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

{
  "cart": {
    "id": 123,
    "cart_token": "<string>",
    "state": "<string>",
    "state_revision": 1,
    "type": "<string>",
    "email": "<string>",
    "phone": "<string>",
    "language_iso": "<string>",
    "currency_code": "<string>",
    "currency_symbol": "<string>",
    "currency_decimal_places": 123,
    "customer_id": 123,
    "buyer_rep_id": 123,
    "enrollment_pack_id": 123,
    "processed": true,
    "email_marketing": true,
    "sms_marketing": true,
    "cv_total": "<string>",
    "qv_total": "<string>",
    "amount_total": 123,
    "sub_total": 123,
    "tax_total": 123,
    "shipping_total": 123,
    "discount_total": 123,
    "subtotal_after_discounts": 123,
    "transaction_fee": 123,
    "enrollment_fee": 123,
    "inclusive_shipping_tax": 123,
    "shipping_discount": 123,
    "remaining_cart_amount_after_points": 123,
    "amount_total_in_currency": "<string>",
    "sub_total_in_currency": "<string>",
    "tax_total_in_currency": "<string>",
    "shipping_total_in_currency": "<string>",
    "discount_total_in_currency": "<string>",
    "subtotal_after_discounts_in_currency": "<string>",
    "transaction_fee_in_currency": "<string>",
    "enrollment_fee_in_currency": "<string>",
    "customer_total_points_in_currency": "<string>",
    "points_applied_amount_in_currency": "<string>",
    "remaining_customer_points_amount_in_currency": "<string>",
    "remaining_cart_amount_after_points_in_currency": "<string>",
    "tax_total_for_display": "<string>",
    "shipping_total_for_display": "<string>",
    "tax_exempt": true,
    "digital_only": true,
    "immutable_items": true,
    "points_enabled": true,
    "price_inclusive_of_tax": true,
    "requires_3ds": true,
    "requires_payment_method": true,
    "vault_without_charge": true,
    "valid_for_checkout": true,
    "valid_for_checkout_pre_payment": true,
    "payment_method_auto_assignable": true,
    "customer_total_points": 123,
    "points_applied": 123,
    "remaining_customer_points": 123,
    "max_applicable_points": 123,
    "total_creditable_points": 123,
    "totals": {
      "gross_subtotal": "<string>",
      "gross_subtotal_in_currency": "<string>",
      "net_subtotal": "<string>",
      "net_subtotal_in_currency": "<string>",
      "item_tax": "<string>",
      "item_tax_in_currency": "<string>",
      "shipping_net": "<string>",
      "shipping_net_in_currency": "<string>",
      "shipping_tax": "<string>",
      "shipping_tax_in_currency": "<string>",
      "total_tax": "<string>",
      "total_tax_in_currency": "<string>",
      "price_inclusive_of_tax": true,
      "tax_label": "<string>"
    },
    "price_inclusive_tax_name": "<string>",
    "payment_account": "<string>",
    "discount_codes": [
      "<string>"
    ],
    "product_discount_codes": [
      "<string>"
    ],
    "shipping_discount_codes": [
      "<string>"
    ],
    "buyer_rep": {
      "id": 123,
      "email": "<string>",
      "full_name": "<string>",
      "image_url": "<string>",
      "external_id": "<string>"
    },
    "volume_rep": {
      "id": 123,
      "email": "<string>",
      "full_name": "<string>",
      "image_url": "<string>"
    },
    "shipping_method": {
      "id": "<string>",
      "name": "<string>"
    },
    "discount_breakdown": {
      "internal_discounts": 123,
      "external_discounts": 123,
      "total_discounts": 123
    },
    "available_shipping_methods": [
      {
        "id": 123,
        "title": "<string>",
        "price": 123,
        "delivery_time_estimate": "<string>",
        "price_label": "<string>"
      }
    ],
    "metadata": {},
    "messages": "<string>",
    "payment_method": {
      "id": 123,
      "type": "<string>",
      "payment_method_type": "<string>",
      "card_network": "<string>",
      "last_four": "<string>",
      "exp_month": "<string>",
      "exp_year": "<string>",
      "logo_url": "<string>",
      "status": "<string>",
      "affirm_id": "<string>",
      "checkout_id": "<string>",
      "created": "<string>",
      "auth_expiration": "<string>",
      "currency": "<string>",
      "amount": 123,
      "session_id": "<string>",
      "intent": "<string>",
      "customer_details": {}
    },
    "available_payment_methods": [
      {
        "id": 123,
        "uuid": "<string>",
        "type": "<string>",
        "name": "<string>",
        "image_url": "<string>",
        "test": true,
        "sandbox": true,
        "customer_details_schema": {},
        "collect_billing_address": true,
        "supported_brands": [
          "<string>"
        ],
        "token_provider": "<string>",
        "tokenize_path": "<string>",
        "bogus_gateway": true,
        "apple_pay": true,
        "apple_pay_recurring_supported": true,
        "apple_pay_merchant_identifier": "<string>",
        "client_id": "<string>",
        "merchant_id": "<string>",
        "sdk_type": "<string>",
        "decrypted_apple_pay_via_paypal": true,
        "integration_key": "<string>"
      }
    ],
    "external_discount": {
      "total": 123,
      "calculated_at": "2023-11-07T05:31:56Z",
      "sources": {}
    },
    "shipping_address": {
      "name": "<string>",
      "address1": "<string>",
      "address2": "<string>",
      "address3": "<string>",
      "city": "<string>",
      "state": "<string>",
      "postal_code": "<string>",
      "country_code": "<string>",
      "subdivision_code": "<string>",
      "phone": "<string>"
    },
    "billing_address": {
      "name": "<string>",
      "address1": "<string>",
      "address2": "<string>",
      "address3": "<string>",
      "city": "<string>",
      "state": "<string>",
      "postal_code": "<string>",
      "country_code": "<string>",
      "subdivision_code": "<string>",
      "phone": "<string>"
    },
    "items": [
      {
        "id": 123,
        "title": "<string>",
        "quantity": 123,
        "price": 123,
        "discount_amount": 123,
        "tax": 123,
        "cv": "<string>",
        "qv": "<string>",
        "cv_total": "<string>",
        "qv_total": "<string>",
        "total": 123,
        "total_after_discounts": 123,
        "enrollment_pack_id": 123,
        "subscription": true,
        "display_to_customer": true,
        "image_url": "<string>",
        "price_in_currency": "<string>",
        "tax_in_currency": "<string>",
        "discount_amount_in_currency": "<string>",
        "total_in_currency": "<string>",
        "total_after_discounts_in_currency": "<string>",
        "line_total_in_currency": "<string>",
        "line_total_after_discounts_in_currency": "<string>",
        "unit_price_display_authoritative": true,
        "free_item": true,
        "allow_subscription": true,
        "enrollment": true,
        "creditable_points": 123,
        "product_title": "<string>",
        "subscription_plan_id": 123,
        "subscription_only": true,
        "subscription_interval": 123,
        "subscription_interval_unit": "<string>",
        "subscription_interval_unit_identifier": "<string>",
        "subscription_price": 123,
        "subscription_price_in_currency": "<string>",
        "subscription_start": "<string>",
        "subscribe_and_save": 123,
        "subscribe_and_save_in_currency": "<string>",
        "subscribe_and_save_for_display": "<string>",
        "metadata": {},
        "errors": [
          {}
        ],
        "subscription_plans": [
          {
            "id": 123,
            "name": "<string>",
            "billing_interval": 123,
            "billing_interval_unit": "<string>",
            "billing_interval_unit_identifier": "<string>",
            "billing_frequency_in_words": "<string>",
            "shipping_interval": 123,
            "shipping_interval_unit": "<string>",
            "volume_interval": 123,
            "volume_interval_unit": "<string>",
            "trial_period": 123,
            "trial_period_unit": "<string>",
            "split_volume": true,
            "allow_max_billing_cycles": true,
            "max_billing_cycles": 123,
            "savings_display_mode": "<string>",
            "savings_label": "<string>",
            "company_default": true,
            "products_count": 123,
            "subscribers_count": 123,
            "price": 123,
            "price_in_currency": "<string>",
            "subscription_start": "2023-11-07T05:31:56Z",
            "subscribe_and_save": 123,
            "subscribe_and_save_in_currency": "<string>",
            "subscribe_and_save_for_display": "<string>"
          }
        ],
        "bundled_items": [
          {
            "variant_id": 123,
            "product_id": 123,
            "product_title": "<string>",
            "variant_title": "<string>",
            "option_titles": [
              "<string>"
            ],
            "quantity": 123,
            "display_to_customer": true,
            "product_bundle_group_id": 123,
            "group_title": "<string>",
            "price": 123,
            "subscription": true,
            "subscription_plan_id": 123
          }
        ],
        "product": {
          "id": 123,
          "title": "<string>",
          "image_url": "<string>",
          "image_path": "<string>",
          "cv": "<string>",
          "tax": 123,
          "sku": "<string>",
          "external_id": "<string>",
          "canonical_url": "<string>",
          "introduction": "<string>",
          "price": 123,
          "price_in_currency": "<string>",
          "tax_in_currency": "<string>",
          "subscription_price": 123,
          "metadata": {},
          "metafields": [
            {
              "id": 123,
              "namespace": "<string>",
              "key": "<string>",
              "value": "<string>",
              "value_type": "<string>",
              "description": "<string>",
              "owner_type": "<string>",
              "owner_id": 123,
              "created_at": "2023-11-07T05:31:56Z",
              "updated_at": "2023-11-07T05:31:56Z",
              "metafield_definition": {
                "id": 123,
                "company_id": 123,
                "namespace": "<string>",
                "key": "<string>",
                "name": "<string>",
                "description": "<string>",
                "value_type": "<string>",
                "validation_rules": "<string>",
                "owner_resource": "<string>",
                "pinned": true,
                "position": 123,
                "locked": true,
                "list_type": true,
                "reference_type": true,
                "supported_validations": [
                  "<string>"
                ],
                "validation_description": "<string>",
                "category_ids": [
                  123
                ],
                "created_at": "2023-11-07T05:31:56Z",
                "updated_at": "2023-11-07T05:31:56Z"
              }
            }
          ],
          "metafields_collection": [
            {
              "key": "<string>",
              "value": "<string>"
            }
          ],
          "product_bundle_groups": [
            {
              "id": 123,
              "title": "<string>",
              "description": "<string>",
              "group_type": "<string>",
              "purpose": "<string>",
              "min_selections": 123,
              "max_selections": 123,
              "selection_type": "<string>",
              "pricing_config": {
                "pricing_type": "<string>",
                "fixed_price": 123,
                "min_price": 123,
                "hidden": true,
                "country_pricing": [
                  {
                    "country_code": "<string>",
                    "enabled": true,
                    "price": "<string>",
                    "wholesale": "<string>",
                    "subscription_price": "<string>",
                    "wholesale_subscription_price": "<string>",
                    "points": "<string>",
                    "cv": 123,
                    "qv": 123,
                    "wholesale_cv": 123,
                    "wholesale_qv": 123
                  }
                ]
              },
              "allow_subscriptions": true,
              "force_subscriptions": true,
              "sort_order": 123,
              "created_at": "2023-11-07T05:31:56Z",
              "updated_at": "2023-11-07T05:31:56Z",
              "images": [
                {
                  "id": 123,
                  "image_url": "<string>",
                  "image_path": "<string>",
                  "position": 123,
                  "dam_asset_code": "<string>"
                }
              ],
              "bundle_group_items": [
                {
                  "id": 123,
                  "quantity": 123,
                  "sort_order": 123,
                  "config": {
                    "price": 123,
                    "pc_price": 123,
                    "resolved_price": "<string>",
                    "resolved_wholesale_price": "<string>",
                    "resolved_cv": "<string>",
                    "resolved_qv": "<string>",
                    "resolved_wholesale_cv": "<string>",
                    "resolved_wholesale_qv": "<string>",
                    "cv": "<string>",
                    "qv": "<string>",
                    "pc_cv": "<string>",
                    "pc_qv": "<string>",
                    "is_default": true,
                    "quantity": 123,
                    "max_quantity": 123,
                    "allow_subscription": true,
                    "force_subscription": true,
                    "has_subscription_plans": true,
                    "subscription_plans": [
                      {
                        "id": 123,
                        "subscription_price_in_currency": "<string>",
                        "subscribe_and_save_in_currency": "<string>",
                        "subscribe_and_save_for_display": "<string>",
                        "wholesale_subscription_price_in_currency": "<string>",
                        "wholesale_subscribe_and_save_in_currency": "<string>",
                        "wholesale_subscribe_and_save_for_display": "<string>"
                      }
                    ],
                    "image_url": "<string>",
                    "available_country_codes": [
                      "<string>"
                    ],
                    "country_prices": {}
                  },
                  "variant": {
                    "id": 123,
                    "title": "<string>",
                    "display_name": "<string>",
                    "image_url": "<string>",
                    "image_path": "<string>",
                    "sku": "<string>",
                    "primary_image": "<string>",
                    "price": 123,
                    "price_in_currency": "<string>",
                    "currency_code": "<string>",
                    "customer_limit": 123,
                    "active_variant_countries": [
                      "<string>"
                    ],
                    "options": [
                      {
                        "title": "<string>",
                        "value": "<string>"
                      }
                    ],
                    "product": {
                      "id": 123,
                      "title": "<string>",
                      "image_url": "<string>",
                      "image_path": "<string>",
                      "cv": "<string>",
                      "cv_in_currency": "<string>",
                      "tax": 123,
                      "tax_in_currency": "<string>",
                      "sku": "<string>",
                      "external_id": "<string>",
                      "canonical_url": "<string>",
                      "introduction": "<string>",
                      "price": 123,
                      "price_in_currency": "<string>",
                      "metadata": {}
                    }
                  }
                }
              ]
            }
          ]
        },
        "variant": {
          "id": 123,
          "title": "<string>",
          "display_name": "<string>",
          "image_url": "<string>",
          "image_path": "<string>",
          "sku": "<string>",
          "primary_image": "<string>",
          "price": 123,
          "price_in_currency": "<string>",
          "currency_code": "<string>",
          "options": [
            {
              "title": "<string>",
              "value": "<string>"
            }
          ],
          "physical": true,
          "unit_of_size": "<string>",
          "height": 123,
          "width": 123,
          "length": 123,
          "unit_of_weight": "<string>",
          "weight": "<string>",
          "hs_code": "<string>"
        }
      }
    ],
    "ship_to": {
      "address1": "<string>",
      "address2": null,
      "address3": null,
      "city": "<string>",
      "country_code": "<string>",
      "country_num_code": 123,
      "default": true,
      "id": 123,
      "name": "<string>",
      "phone": "<string>",
      "postal_code": "<string>",
      "state": "<string>",
      "subdivision_code": null
    },
    "bill_to": {
      "address1": "<string>",
      "address2": null,
      "address3": null,
      "city": "<string>",
      "country_code": "<string>",
      "country_num_code": 123,
      "default": true,
      "id": 123,
      "name": "<string>",
      "phone": "<string>",
      "postal_code": "<string>",
      "state": "<string>",
      "subdivision_code": null
    },
    "attribution": {
      "id": 123,
      "email": 123,
      "fluid_rep_id": 123,
      "external_id": 123,
      "share_guid": 123,
      "username": 123
    },
    "agreements": [
      {
        "id": 123,
        "title": "<string>",
        "show_at_checkout": true,
        "default_checked": true,
        "show_path": "<string>",
        "enrollment_pack_id": 123,
        "required": true
      }
    ],
    "country": {
      "currency_code": "<string>",
      "currency_symbol": "<string>",
      "id": 123,
      "iso": "<string>",
      "iso3": "<string>",
      "iso_name": "<string>",
      "name": "<string>",
      "price_inclusive_of_tax": true,
      "price_inclusive_tax_name": "<string>",
      "province_required": true,
      "tax_enabled": true,
      "tax_standard_rate": 123
    },
    "company": {
      "bundle_subscriptions": true,
      "checkout_primary_button_color": "<string>",
      "checkout_primary_text_color": "<string>",
      "checkout_secondary_button_color": "<string>",
      "checkout_secondary_text_color": "<string>",
      "collect_email_marketing": true,
      "collect_phone": true,
      "collect_sms_marketing": true,
      "favicon_url": "<string>",
      "fluid_shop": "<string>",
      "id": 123,
      "isolated_payment_tokens": true,
      "kount_environment": "sandbox",
      "kount_client_id": "150953359757648",
      "logo_url": "<string>",
      "name": "<string>",
      "order_on_behalf": true,
      "primary_domain_hostname": "<string>",
      "require_billing_zip": true,
      "require_phone": true,
      "reward_points_apply_to_subtotal": true,
      "reward_points_enabled": true,
      "reward_points_label_singular": "<string>",
      "reward_points_label_plural": "<string>",
      "subdomain": "<string>"
    },
    "recurring": [
      {
        "subtotal": 123,
        "subtotal_in_currency": "<string>",
        "interval": 123,
        "interval_unit": "<string>",
        "interval_unit_identifier": "<string>",
        "subtotal_for_display": "<string>",
        "start_date": "<string>"
      }
    ],
    "enrollment_pack": {
      "enrollment_pack_id": 123,
      "slug": "<string>",
      "token": "<string>",
      "title": "<string>",
      "description": "<string>",
      "enrollment_fee": 123,
      "additional_volume": 123,
      "canonical_url": "<string>",
      "enrollment_fee_in_currency": "<string>",
      "price": "<string>",
      "price_in_currency": "<string>",
      "subscription_price": "<string>",
      "subscription_price_in_currency": "<string>",
      "images": [
        {
          "id": 123,
          "external_id": "<string>",
          "image_path": "<string>",
          "image_url": "<string>",
          "image_url_i18n": {},
          "position": 123,
          "relateable_id": 123,
          "relateable_type": "<string>",
          "uuid_v7": "<string>",
          "created_at": "2023-11-07T05:31:56Z",
          "updated_at": "2023-11-07T05:31:56Z"
        }
      ],
      "items": [
        {
          "id": 123,
          "title": "<string>",
          "quantity": 123,
          "price": 123,
          "tax": 123,
          "cv": "<string>",
          "qv": "<string>",
          "cv_total": "<string>",
          "qv_total": "<string>",
          "cv_in_currency": "<string>",
          "qv_in_currency": "<string>",
          "total": 123,
          "total_after_discounts": 123,
          "enrollment_pack_id": 123,
          "subscription": true,
          "display_to_customer": true,
          "price_in_currency": "<string>",
          "tax_in_currency": "<string>",
          "total_in_currency": "<string>",
          "total_after_discounts_in_currency": "<string>",
          "line_total_in_currency": "<string>",
          "line_total_after_discounts_in_currency": "<string>",
          "unit_price_display_authoritative": true,
          "allow_subscription": true,
          "enrollment": true,
          "creditable_points": 123,
          "product_title": "<string>",
          "subscription_plan_id": 123,
          "subscription_only": true,
          "subscription_interval": 123,
          "subscription_interval_unit": "<string>",
          "subscription_interval_unit_identifier": "<string>",
          "subscription_price": 123,
          "subscription_price_in_currency": "<string>",
          "subscription_start": "<string>",
          "subscribe_and_save": 123,
          "subscribe_and_save_in_currency": "<string>",
          "subscribe_and_save_for_display": "<string>",
          "metadata": {},
          "errors": [
            {}
          ],
          "subscription_plans": [
            {
              "id": 123,
              "name": "<string>",
              "billing_interval": 123,
              "billing_interval_unit": "<string>",
              "billing_interval_unit_identifier": "<string>",
              "billing_frequency_in_words": "<string>",
              "shipping_interval": 123,
              "shipping_interval_unit": "<string>",
              "volume_interval": 123,
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{
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}