WATI's decent if you've got the budget, but honestly it's way too much for anyone just starting out.
The way it works under the hood: you hook into Meta's official WhatsApp Business API, get your number verified, then set up automated replies and chat flows. The chatbot side is mostly keyword triggers or button menus - not proper AI, just basic logic.
Cheaper options doing the same thing on the same Meta API are Interakt and Waplify.io. They'll save you a chunk.
One thing that catches most people out: Meta has to approve every message template before you can send anything. that approval takes a day or three, and nobody mentions it upfront.
What kind of automation are you trying to build?