Here's the difference, because the names are a genuine mess. The free WhatsApp Business app is a phone in someone's hand — it can fire off a canned "we're closed", but a person still has to read every message and reply. The WhatsApp Business API — and its modern flavour, the Cloud API — isn't an app at all. It's a connection other software plugs into, so something can read, reply and book while you sleep.
For booking, that one line is the whole story. The app is manual. The API is what makes real automation possible. Everything below is just detail on those two facts — and the one thing you actually need underneath both.
Tier one: the free app. One number, one main phone. You get greeting messages, away messages, saved quick replies, chat labels and a catalogue. It feels close to automation, and it isn't. An away message sends the same line to everyone — the same "thanks, we're closed, back tomorrow" to a first-timer and to a ten-year regular. It can't read can I move Saturday to 4?, it can't check your diary, and it can't book anyone in. It's built for one owner, one phone, replying by hand.
Tier two: the API, and the Cloud API. This is the part that trips people up. The API isn't something you open and log into. It's a doorway other software connects to your number. The Cloud API is simply Meta's hosted version of it — the modern default — so nobody has to run a server in a back room.
What it unlocks is the real list: an agent that answers 24/7, several people working one number at once, and message templates — the pre-approved texts you're allowed to send first, before a customer has replied, with opt-in rules attached. This is the only tier where "answers and books on its own" is even on the table.
The API isn't an app you open. It's a socket — and something still has to plug in.
Because that's the catch nobody mentions: the API on its own does nothing. It's plumbing. Something has to sit on top of it to turn can I get in Saturday? into an actual appointment in your book. One more thing worth knowing — a number running on the API can't also live in the ordinary Business app at the same time. A number does one job or the other.
Tier three: what a salon actually needs. You don't have to weigh these up in the abstract. You need one outcome — something that answers your WhatsApp and books people in, day and night, on the number your clients already message. That takes two pieces: Cloud API access, and a layer on top that knows your diary, your prices and your regulars.
Here's the honest bit. You don't build either piece, and you don't need an agency to stitch them together. A lot of the quotes owners get are for building that top layer from scratch, plus a monthly retainer to babysit it. You don't need a custom project to have something answer and book — you need one ready-made receptionist connected to your existing number.
That's what Luna is: the Cloud API and the receptionist on top, already built, on the WhatsApp your clients already use, for a flat £69 a month. No developer, no agency, no server in a back room.
Want to see the finished thing before any of the wiring? Message her on the salons page like one of your clients and try to catch her out. Running something that isn't a salon? We build custom agents too. Or read the rest of the notes.