Both auth and notifications get extraordinary complex at even minimal scale. Obviously each business needs to decide which areas make sense to invest from tech

Both auth and notifications get extraordinary complex at even minimal scale. Obviously each business needs to decide which areas make sense to invest from tech perspective but LinkedIn and AirBnB each spend around $20m/year just on their notification systems. https://medium.com/airbnb-engineering/airbnbs-promotions-and-communications-platform-6266f1ffe2bd https://medium.com/airbnb-engineering/airbnbs-promotions-and... https://engineering.linkedin.com/blog/2018/03/air-traffic-controller--member-first-notifications-at-linkedin https://engineering.linkedin.com/blog/2018/03/air-traffic-co...