On Google Spreadsheet / Google Form submission, push new entry to a MailChimp subscription list with an `onformsubmit` trigger. Uses the MailChimp 3.0 API and Google Apps Script.

mailchimp-googlescript.txt

/** 
* Mailchimp API v3 
* Add a subscriber to a list with interests on Google Form submit
*
* Updated to 3.0 from https://gist.github.com/acarrillo/5772508
*
* Edit the Google Sheet connected to your form
* Menu > Tools > Script Editor
* Copy and paste this into the file, remove anything there already
* Update the variables in the top section
* If you want to use interests insert / edit that part too
* In the script editor hit run > myFunction to create the trigger
*
* 
*/

// Your API Key from https://us3.admin.mailchimp.com/account/api/
var API_KEY = 'xxxxxxxxxxxxxxxxxxx-yyy';

// get the right server by taking yyy from the API key
// replace bbbbb with the list id you wish to work on
var mc_base_url = 'https://yyy.api.mailchimp.com/3.0/lists/bbbbbbbbb/members';

// subscribed (no opt in confirmation)
// unsubscribed 
// cleaned 
// pending (triggers double optin) 
// transactional
var status = 'pending';

// What is the question name of the email address in the form?
var fieldEmail = 'Your Email address';
 
/**
 * Uses the MailChimp 3.0 API to add a subscriber to a list.
 */
function sendToMailChimp(em){
  Logger.log('sendToMailChimp');
  var interests = {
    "cccccccccc":true // add in the ID of the Interest (under the List > Interest Categories)
  };
  var payload = {
    "email_address": em,
    "status": status,
    "interests" : interests
  };
  var headers = {
    "Authorization": 'Basic ' + Utilities.base64Encode('anystring:' + API_KEY, Utilities.Charset.UTF_8)
  };
  var options = {
    "method": "post",
    "payload": JSON.stringify(payload),
    "headers": headers,
    "muteHttpExceptions" : true
  };
  
  Logger.log(options);
  
  try {
    
    var response = UrlFetchApp.fetch(mc_base_url,options);
    
    if(response.getResponseCode() === 200) {
      // all good!
      Logger.log('Success');
      Logger.log(response);
    } else{
      Logger.log('Issues');
      Logger.log(response);
    }
  } catch (err) {
    // handle the error here
    Logger.log('Error');
    Logger.log(err);
  }
  
  
}
 
/**
 * Trigger function. Based on Google Script tutorial.
 * @param {Object} e The event parameter for form submission to a spreadsheet;
 *     see https://developers.google.com/apps-script/understanding_events
 */
function onFormSubmit(e) {
  Logger.log('on Form Submit');
  Logger.log(e);
  Logger.log(e.namedValues[fieldEmail]);
  var em = e.namedValues[fieldEmail][0];
  Logger.log(em);
  
  if (em.length){
    sendToMailChimp(em);
  }else{
    Logger.log('Error: couldnt find an email address in submission');
  }
   
}
 
/**
 * Main function. Creates onFormSubmit trigger.
 */
function myFunction(){
  // Was separated line by line for debugging purposes.
  var sheet = SpreadsheetApp.getActive();
  var a = ScriptApp.newTrigger("onFormSubmit");
  var b = a.forSpreadsheet(sheet);
  var c = b.onFormSubmit();
  var d = c.create();
}