Automatically update your YNAB 'Home Value' tracking account with Zillow's Zestimate data

ynabZestimate.gs

function updateYnabHomeZestimate() {
  var accessToken = 'YNAB token goes here' // Your YNAB Personal Access Token
  var zwsid = 'zwsid goes here' // Your Zillow ZWSID
  var budgetName = 'budget name goes here' // The name of your budget
  var accountName = 'home value account name goes here' // The name of your home value tracking account
  var address = '1657 Notrealaddress Drive, Redding, CA 96001' // Home address
  
  // YNAB API settings
  var url = 'https://api.youneedabudget.com/v1'
  var headers = {
    "Authorization": "Bearer " + accessToken,
    "Content-Type":"application/json; charset=utf-8"
  }
  
  // Get all budgets, find our budget by name
  var budgets = JSON.parse(UrlFetchApp.fetch(url + '/budgets', {'headers': headers})).data.budgets
  var budget = findObjectByKey(budgets, 'name', budgetName)
  
  // Get all accounts in the budget, find our home value tracking account by name
  var accountsUrl = url + '/budgets/' + budget.id + '/accounts'
  var accounts = JSON.parse(UrlFetchApp.fetch(accountsUrl, {'headers': headers})).data.accounts
  var account = findObjectByKey(accounts, 'name', accountName)
  var accountValue = account.balance / 1000
  
  // Get the zestimate
  var zestimate = parseFloat(getDeepSearchResults(zwsid,address).getChild('zestimate').getChild('amount').getValue())
  
  // If the totals don't match, update the value in YNAB
  if (zestimate != accountValue) {
    var transactionData = {
      'transaction': {
        'account_id': account.id,
        'date': Utilities.formatDate(new Date(), "UTC", "yyyy-MM-dd"),
        'amount': ((zestimate - accountValue) * 1000).toString(),
        'payee_name': 'Zestimate Automation',
        'memo': 'Entered automatically by Google Apps Script automation',
        'cleared': 'cleared',
        'approved': true
      }
    }
    var options = {
      'method': 'post',
      'payload': JSON.stringify(transactionData),
      'headers': headers
    }
    var transactionUrl = url + '/budgets/' + budget.id + '/transactions'
    var result = UrlFetchApp.fetch(transactionUrl, options)
  }
}

// Function to retrieve detailed 
function getDeepSearchResults(zwsid, address) {
  var addressArray = splitAddress(address)
  var endpoint = 'http://www.zillow.com/webservice/GetDeepSearchResults.htm'
  var params = [
    'zws-id='+zwsid,
    'address='+addressArray['address'],
    'citystatezip='+addressArray['cityStateZip']
  ]
  var requestUri = endpoint.concat("?", params.join('&')) 
  var xmlData = XmlService.parse(UrlFetchApp.fetch(requestUri).getContentText())
  var rootElement = xmlData.getRootElement()
  var result = rootElement.getChild('response').getChild('results').getChild('result')
  return result
}

// Function to convert an address into an array for Zillow API usage
function splitAddress(address) {
  var addressArray = address.split(',')
  return {
    'address': addressArray[0].trim(),
    'cityStateZip': ''.concat(addressArray[1].trim(),', ', addressArray[2].trim())
  }
}

// Function to find objects in an array of objects by key value
function findObjectByKey(array, key, value) {
  for (var i = 0; i < array.length; i++) {
    if (array[i][key] === value) {
      return array[i];
    }
  }
  return null;
}