Is there an API or ready-made libraries for adding contacts to iOS, Android, Windows Phone phonebooks?

Question

API

It is necessary to automatically add contacts of new customers of the online store to the manager's phone book for subsequent search and communication via Viber, WhatsApp.
For which of the listed platforms is there a corresponding API? Are there ready-made solutions in scripting languages ​​that can be used?

Answer 1

I haven’t gone deep into viber yet, but they say somehow through https://www.mobizen.com/ they do it.
There are 2 options for whatsapp: parse whatsapp web and WHAnonymous/Chat API.
In the case of whatsapp web, the main problem is script maintenance. In the case of the Chat API, it is impossible to use whatsapp on the phone in parallel.
In fact, I already tried and did all this. The blog has a small article on this topic and the API is ready on my website DATA5
data5.ru/blog/index.php?controller=post&action=vie...