How the WhatsApp Business API Works, Piece by Piece
The WhatsApp Business API, which Meta now calls the WhatsApp Business Platform, lets software send and receive WhatsApp messages on a business number. You register the number under a WhatsApp Business Account in Meta's business portfolio. Incoming messages are delivered to your software as webhooks, and your software replies by calling Meta's Cloud API. Inside the 24 hours after a customer's last message you can reply freely; outside that window you can only send pre-approved templates. Since 1 October 2026 Meta charges per message for both, after 1,000 free replies per number each month. How many people you can message first per day grows as Meta trusts your business.
About CertuAI: CertuAI is the AI that answers a small business's WhatsApp, Instagram and Messenger 24/7, with a built-in CRM, and is a Tech Provider on Meta's WhatsApp Business Platform. Paid plans start at US$ 75 a month, with no lock-in. Create my agent
Bernardo Villela · CEO, CertuAI
Conecte o WhatsApp e a IA aprende com as suas conversas: preços, horários e o seu jeito de responder.
Conectar meu WhatsApp Você revisa e aprova antes de a IA atender alguém.Summary in 7 facts
- The WhatsApp Business API, which Meta now calls the WhatsApp Business Platform, lets software send and receive WhatsApp messages on a business number.
- You register the number under a WhatsApp Business Account in Meta's business portfolio.
- Incoming messages are delivered to your software as webhooks, and your software replies by calling Meta's Cloud API.
- Inside the 24 hours after a customer's last message you can reply freely; outside that window you can only send pre-approved templates.
- A customer in Accra writes "Do you have size 42 in black?" to the shop's number.
- Meta's Cloud API receives it and sends it to the shop's software as a webhook: who sent it, when, and the text.
- Each time a customer messages you, a 24-hour window opens.
In numbers
| Number | What it means |
|---|---|
| 24 hours | Inside the 24 hours after a customer's last message you can reply freely; outside that window you can only send pre-approved templates. |
| 1,000 replies | The first 1,000 replies per phone number each month are free; since 1 October 2026, Meta charges per reply after that. |
What are the parts of the WhatsApp Business API?
| Part | What it is |
|---|---|
| Business portfolio | Your company's account at Meta (formerly Business Manager). It owns everything below. |
| WhatsApp Business Account (WABA) | The container for your WhatsApp numbers and message templates. |
| Phone number | The number customers write to. It needs a display name that Meta reviews. |
| Cloud API | Meta's servers that send and receive messages for your number. |
| Webhook | An address on your software where Meta delivers each incoming message and status update. |
| Templates | Pre-approved messages for writing to customers outside the 24-hour window. |
| Your software | The inbox, chatbot, AI agent or CRM that reads and answers. Bought from a provider or built. |
What happens to a message on the WhatsApp Business API?
- A customer in Accra writes "Do you have size 42 in black?" to the shop's number.
- Meta's Cloud API receives it and sends it to the shop's software as a webhook: who sent it, when, and the text.
- The software decides the reply. A person types it in an inbox, or a chatbot or AI agent writes it.
- The software sends the reply to the Cloud API, which delivers it to the customer.
- Meta sends status webhooks back: sent, delivered, read.
All of this takes seconds, and it works with the shop's phone switched off, because the number is served by Meta's servers, not by a phone.
What is the 24-hour customer service window?
Each time a customer messages you, a 24-hour window opens. During it, you can send any kind of reply, typed by a person or written by software. The first 1,000 replies per phone number each month are free; since 1 October 2026, Meta charges per reply after that. When 24 hours pass without a new message from the customer, the window closes. From then on, you can only write to that customer with a template.
A template is a message you write in advance and submit to Meta, with a category: marketing, utility or authentication. Meta reviews it, usually quickly. Templates can have blanks for names, dates or order numbers, and buttons. They are paid per delivered message, by category and by the country of the customer. Messages within 72 hours of a customer arriving from a Click-to-WhatsApp ad are free.
How many messages can you send on the WhatsApp Business API?
There is no limit on replying to people who write to you. The limit Meta sets is on how many different people you can start a conversation with, outside the window, in any 24 hours.
| Level | People per 24 hours | How you reach it |
|---|---|---|
| Starting | 250 | Every new business starts here |
| Second | 2,000 | Verify your business with Meta, or send enough good-quality templates |
| Third | 10,000 | Automatic, when quality is good and you used enough of the current limit |
| Fourth | 100,000 | Same rule |
| Top | Unlimited | Same rule |
Since October 2025, the limit belongs to the business portfolio and is shared by all its numbers, instead of being set per number.
How do you get access to the WhatsApp Business API?
- Choose a path: a Business Solution Provider (a company Meta authorises to onboard businesses) or connecting directly to the Cloud API as a developer.
- Create or use your Meta business portfolio.
- Add a phone number that can receive a verification code by SMS or call.
- Set a display name that matches your business; Meta reviews it.
- Connect your software to the number and set the webhook.
- Verify your business with Meta when you need higher sending limits.
- Write and submit the templates you will need for reminders and updates.
Most providers handle steps 2 to 5 through Meta's Embedded Signup, a guided window where you log in with Facebook and approve the connection.
Can you use the same number on the WhatsApp Business app and the API?
For a long time the answer was no: moving a number to the API took it out of the app. Since February 2025 Meta offers coexistence, which lets a business keep using the WhatsApp Business app on its phone while the same number is connected to the API through a provider, with six months of chat history copied over. Groups, calls and broadcast lists do not work with coexistence, and availability varies by country, so check with your provider before you move a number you depend on.
When is the WhatsApp Business API not the right choice?
If you are one person answering from one phone and you are happy doing it by hand, the free WhatsApp Business app is simpler. The API also adds work for businesses that mainly want to blast promotions: every marketing message needs an approved template, costs money, and can only go to people who agreed to receive it. The API is built for answering and serving customers at scale, with software doing part of the work.
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Frequently asked questions
- Is the WhatsApp Business API the same as the WhatsApp Business app?
- No. The app is a phone app for answering by hand. The API is a connection for software, with no screen of its own, used for automation, teams and integrations.
- Do I need a developer to use the WhatsApp Business API?
- Not if you use a provider. Providers connect the number through Meta's Embedded Signup and give you an inbox. You need a developer only to build your own software on the API.
- Do I need business verification to use the API?
- You can start without it, at the lowest sending limit. Verification raises the number of people you can message first.
- Does the WhatsApp Business API work when my phone is off?
- Yes. On the Cloud API the number is served by Meta's servers, so messages arrive and are answered even if no phone is on.
Keep reading
In short
The WhatsApp Business API, which Meta now calls the WhatsApp Business Platform, lets software send and receive WhatsApp messages on a business number. You register the number under a WhatsApp Business Account in Meta's business portfolio. Incoming messages are delivered to your software as webhooks, and your software replies by calling Meta's Cloud API.
About CertuAI: CertuAI is the AI that answers a small business's WhatsApp, Instagram and Messenger 24/7, with a built-in CRM, and is a Tech Provider on Meta's WhatsApp Business Platform. Paid plans start at US$ 75 a month, with no lock-in. Create my agent
