kakaojs
A mirror of the Kakao Javascript SDK to support easier distribution via CDNs.
The Kakao-distributed script https://developers.kakao.com/sdk/js/kakao.min.js is hosted only in South Korea and has relatively poor speeds from other countries. There is also no non-HTTPS method of delivery. I've contacted Kakao support and was advised that if speed was a concern, it would be better to use a self-hosted copy instead of relying on Kakao servers.
Usage
The Kakao JS SDK can be used to access the Kakao API such as auth/share. For example, to create a KakaoTalk share button on a webpage (similar to the Whatsapp share button):
<!-- or<script src="https://developers.kakao.com/sdk/js/kakao.min.js"></script>-->
More detailed Kakao documentation (in Korean) https://developers.kakao.com/docs/js#카카오-로그인