The Gmail Mail Merge addon can now import the email addresses of subscribers from your MailChimp mailing lists into Google Sheets. If you wish to send emails to your subscribers directly from Gmail, instead of using MailChimp mail servers, this is the way to go.

As a developer, you can use Google Apps Script to import subscriber lists, HTML campaigns, performance reports and any other data from MailChimp to Google Sheets for analysis. You can use the MailChimp OAuth2 library but in this example, we’ll use the developer key directly to connect to MailChimp.

Get the MailChimp Developer Key

In your Mailchimp account, navigate to the Account page. In the drop-down menu, select Extras, and then API keys. Click Create A Key and make a note of it.

Google Apps Script - Get MailChimp Audiences

const MAILCHIMP_API_KEY = '<>';

// MailChimp API key includes the data center id
// that your MailChimp account is associated with
const makeHttpRequest = (endpoint, params = {}) => {
  const [, mailchimpDataCenter] = MAILCHIMP_API_KEY.split('-');
  const url = `https://${mailchimpDataCenter}.api.mailchimp.com/3.0/${endpoint}`;
  const qs = Object.keys(params)
    .map((key) => `${key}=${params[key]}`)
    .join('&');
  const apiUrl = qs ? `${url}?${qs}` : url;
  const request = UrlFetchApp.fetch(apiUrl, {
    method: 'GET',
    headers: {
      Authorization: `Basic ${Utilities.base64Encode(`labnol:${MAILCHIMP_API_KEY}`)}`,
    },
  });
  return JSON.parse(request);
};

const getListMembers = (id, offset) => {
  const { members } = makeHttpRequest(`lists/${id}/members`, {
    count: 100,
    offset,
    fields: 'members.email_address',
    status: 'subscribed',
    sort_field: 'last_changed',
    sort_dir: 'DESC',
  });
  return members.map(({ email_address: email }) => [email]);
};

// Get a list of all subscribers of a specific
// MailChimp mailing list, you can retrieve the email address,
// name and subscription statues of subscribers
const getMailChimpListMembers = (id) => {
  let hasMore = true;
  let data = [];
  do {
    const emails = getListMembers(id, data.length);
    data = [...data, ...emails];
    hasMore = emails.length > 0;
  } while (hasMore);
  return data;
};

// Get a list of all audiences / lists from MailChimp
const getMailChimpLists = () => {
  const params = {
    count: 10,
    fields: 'lists.id,lists.name',
    sort_field: 'date_created',
    sort_dir: 'DESC',
  };
  const { lists = [] } = makeHttpRequest('lists', params);
  return lists.map(({ id, name }) => ({
    id,
    name,
    members: getMailChimpListMembers(id),
  }));
};

The GetMailChimpLists method will bring all the lists and associated email addresses in a JSON object that you can easily write to Google Sheets using the SpreadsheetApp service.