curl --request POST \
  --url https://app.fliqr.ai/api/contacts/{contact_id}/cart/{product_id} \
  --header 'Content-Type: application/x-www-form-urlencoded' \
  --header 'X-ACCESS-TOKEN: <api-key>' \
  --data quantity=123

const options = {
  method: 'POST',
  headers: {
    'X-ACCESS-TOKEN': '<api-key>',
    'Content-Type': 'application/x-www-form-urlencoded'
  },
  body: new URLSearchParams({quantity: '123'})
};

fetch('https://app.fliqr.ai/api/contacts/{contact_id}/cart/{product_id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://app.fliqr.ai/api/contacts/{contact_id}/cart/{product_id}"

payload = { "quantity": "123" }
headers = {
    "X-ACCESS-TOKEN": "<api-key>",
    "Content-Type": "application/x-www-form-urlencoded"
}

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

print(response.text)

{
  "success": true
}