If you sell over WhatsApp and you have reached the point of searching for "WhatsApp Business API", it is usually because you hit one of three walls: you cannot share the number with your team, you cannot message someone after a few hours have passed, or you want an automated reply and cannot find where to set one up.
This explains what each thing is, why Meta's bill works the way it does, and where businesses get stuck. No invented figures: Meta's rates vary by country and category, so what follows is how they are calculated and where to check them, not a number that will be stale in three months.
There are three WhatsApps, and only one works for a company
Regular WhatsApp. The one on your phone. One handset, one person.
WhatsApp Business (the app). Free, with a catalogue, labels and quick replies. Fine for a sole trader or a small shop. Its limits show up fast: it lives on a phone, shares badly, leaves no usable record, and — this is the one that hurts — it leaves the company the day the person holding the phone does.
WhatsApp Business Platform (the API). Not an app: a channel. The number stops living on a handset and starts living in a system. Several people can answer at once, everything is logged, and it can be wired to a CRM or an assistant. It is what businesses use when more enquiries arrive than one person can read.
One detail that catches almost everyone: a number registered on the API stops working in the phone app. The migration is one-way. Decide before, not halfway through.
Meta charges per conversation, not per message
This is the point that causes the most confusion, and the one that determines your bill.
Meta does not count individual messages. It counts conversations: a 24-hour window inside which every message exchanged falls under the same charge. What that conversation costs depends on two things:
- The category. Marketing, utility, authentication or service. A conversation the customer starts (service) is priced differently from one you start to promote something.
- The country. The UK, Spain, Mexico and India are priced very differently.
The practical consequence: it is far cheaper when the customer messages first. A business answering inbound enquiries has a bill of a different order from one running broadcast campaigns. Official rates are published in Meta's documentation and revised periodically — check yours before doing sums.
The 24-hour window, and why templates exist
Within 24 hours of the customer's last message you can write whatever you like, in whatever words. After 24 hours, you can only write using a template Meta approved in advance.
This is not arbitrary: it is what stops WhatsApp becoming a spam channel. But it has real consequences for how you sell:
- If a customer asks on Friday afternoon and you reply on Monday, you can no longer write freely. You need a template.
- Templates go to review and can be rejected. Ones that read as promotion dressed as notification get turned down.
- Which is why useful follow-up happens inside the window. A nudge 18 hours after the last message needs no template; one at 30 hours does.
It is one of the reasons replying quickly is not only commercially better — it is cheaper and operationally simpler.
Where everyone gets stuck
After walking a few businesses through onboarding, it is always the same three.
1. Business verification. Meta asks you to verify the business in Business Manager: documents, address, sometimes a call. If the legal name does not match the register exactly, it is rejected. This is the step that eats the most days, and nearly always over a single letter.
2. The display name. What the customer sees at the top of the chat. Meta reviews it and rejects names unrelated to the verified brand. Choosing badly means starting again.
3. Number quality. Every number carries a quality score that falls when people block or report it. Drop far enough and Meta limits how many unique people you can message per day — or suspends the number. You protect it by replying fast and not broadcasting to cold lists.
Do you need the API?
Honestly: if you get twenty enquiries a month and one person handles them, no. The free app is fine and the API is a complication you do not need.
It earns its place when one of these is true:
- More enquiries arrive than one person can answer in time.
- Several people need to work the same number.
- You want conversations landing in your CRM, not on someone's phone.
- A large share arrives out of hours and goes cold.
That last one moves the most money in considered-purchase businesses. We put numbers on it in The weekend problem.
If you already have AI in WhatsApp
Two things get conflated. The AI WhatsApp ships with helps the person typing — it does not represent your business, and it knows nothing about your catalogue, your prices or your calendar. We go through the difference in Zatio vs Meta AI.
Your own assistant is a different thing: it answers with your data, qualifies, and books. The gap shows on the first specific question a customer asks.
We handle the registration, verification and templates so you never open Business Manager — that is the WhatsApp integration page. And if you want to see what the late-reply gap costs you specifically, the calculator puts it in pounds using your own numbers.