Mass WhatsApp campaign automation: how it works behind the scenes

Sending messages to a small list is trivial. The problem shows up at scale: when there are millions of leads, processing everything at once brings down any system that wasn't designed for it.

The solution we built processes leads via streaming instead of loading everything into memory at once, and uses asynchronous queues (SQS) on AWS to spread the sends over time, without overloading the WhatsApp API or the backend itself.

A real-time metrics dashboard shows the progress of the send as it happens — how many messages were delivered, how many failed, how much is left. And a credit system controls usage and billing for each client on the platform.

It's a good example of automation that only pays off at scale: for a few sends, it's not worth the investment in all this infrastructure. But past a certain volume, this is what separates a campaign that works from one that crashes.