This script downloads all of your lds.org contacts as a vCard file which can be imported into Google Contacts, MacOS Contacts, and many other contact managers. Sign in to lds.org, then open the developer console (http://debugbrowser.com/#chrome) and paste the following code into the console.

lds_contacts.js

// First, get the unit number.
const getUnitNumber = fetch('https://www.lds.org/mobiledirectory/services/ludrs/1.1/mem/mobile/current-user-unitNo', {
  credentials: 'include',
})
.then(response => response.json())
.then(response => response.message);

// Then download all contacts.
const getContacts = getUnitNumber.then(unitNumber => fetch(`https://www.lds.org/mobiledirectory/services/v2/ldstools/member-detaillist-with-callings/${unitNumber}`, {
  credentials: 'include',
}))
.then(response => response.json());

// Finally, turn into vCard, then download the vCard file as 'members.vcf'.
getContacts.then(vcard).then(saveAs.bind(this, 'members.vcf'));

/* ************************************************************************** */

// Takes the JSON response and returns a string of vCard contact entries.
function vcard(response) {
  return response.households.reduce((members, hh) => {
    for (let p of [hh.headOfHouse, hh.spouse]) {
      if (!p) continue;

      const phone = (p.phone || '').trim();
      const email = (p.email || '').trim();

      let addr = hh.desc1 || '';
      if (hh.desc2) addr += ' ' + hh.desc2;

      members += `BEGIN:VCARD
VERSION:3.0
N:${p.surname};${p.givenName};;;
EMAIL;type=INTERNET;type=HOME;type=pref:${email}
TEL;type=HOME;type=VOICE;type=pref:${phone}
ADR;type=HOME;type=pref:;;${addr};;;;
END:VCARD
`;
    }
    return members;
  }, '');
}

// Takes a filename and a string and downloads the given text with the provided filename.
function saveAs(filename, text) {
  const element = document.createElement('a');
  element.setAttribute('href', 'data:text/plain;charset=utf-8,' + encodeURIComponent(text));
  element.setAttribute('download', filename);
  element.style.display = 'none';
  document.body.appendChild(element);
  element.click();
  document.body.removeChild(element);
}