Hacker News Reader

Ads, sales, new partnerships with companies, etc WhatsApp doesn't have any of those

They used to have the 1 dollar per year payment for users. With the amount of users they had, that probably covered all of their cost and then some.

They have at least sales and partnerships: https://business.whatsapp.com/

They do now. The article is from 2015.

Nowadays that it's Meta. Back in the day it was just a end-user chat platform, and pretty simple.