mailchimp.js

axios({
  method: 'post',
  url: `https://us19.api.mailchimp.com/3.0/lists/${listId}/members/`,
  data: JSON.stringify({
    email_address: '[email protected]',
    status: 'subscribed',
  }),
  headers: {
    Authorization: `Basic ${Buffer.from(`apikey:${API_KEY}`).toString('base64')}`,
    'content-type': 'application/json',
  },
})
  .then((response) => console.log(response))
  .catch((error) => console.log(error));