WhatsApp Business API: how it works and what it costs.

The app, and the platform

The WhatsApp Business app is made for a person answering from a phone. The WhatsApp Business Platform — what most people call the WhatsApp Business API — is for software: a CRM, a booking system or an AI agent sends and receives messages on the business's number through an API. Meta hosts it as the Cloud API. Every AI agent we build for clients uses it.

Two kinds of messages

Free-form messages are ordinary replies — text, images, voice notes, documents. They can only be sent inside a customer service window.

Template messages are pre-written messages, with variables, that Meta must approve before use. They are the only way for a business to start a conversation or to write outside a customer service window. Each template has a category: marketing, utility (an update about something the customer did — a booking, an order) or authentication (a one-time code).

The customer service window

When a customer writes to the business, a 24-hour customer service window opens. Inside it, the business can reply with free-form messages. Once it closes, only a template can restart the conversation. Meta also defines a “free entry point” window: when a customer writes after tapping a Click to WhatsApp ad and the business replies inside the customer service window, that reply is not charged and opens a free entry point window, which Meta says “may remain open for up to 7 days”.

How Meta charges today

Meta's documentation is explicit: “Effective July 1, 2025, Meta charges on a per-message basis”, replacing the earlier conversation-based model. Businesses are only charged when a message is delivered, and the rate depends on the message's category and on the country calling code of the recipient's number — so the same reminder costs a different amount in Nairobi, Paris or São Paulo. Since 1 October 2026, replies inside the customer service window are no longer free without limit (see below).

• Free: messages customers send to the business.
• Free, up to a limit: service messages — Meta's name for non-template replies inside an open customer service window. Each business phone number has 1,000 free delivered service messages per month; they do not roll over, and from the 1,001st the messages are charged.
• Free: marketing, utility, authentication and service messages sent inside a free entry point window.
• Charged: every other delivered template — marketing, utility (inside or outside the customer service window), authentication — at the rate of its category and the recipient's country.

What changed on 1 October 2026

On 1 October 2026 (in the timezone of each messaging account), Meta “resumed charging, on a per-message basis, for messages that were previously free”: service messages, free since 1 November 2024, and utility templates sent inside an open customer service window, free since 1 July 2025. Two consequences for a business on the platform:

• A payment method is now required for replies too. Meta warned that businesses without a payment method on file by 30 September 2026 could see their service messages stop being delivered.
• The free tier is per number. The 1,000 free service messages a month belong to each business phone number. Beyond them, service messages stay free only for eligible government and non-profit organisations, a policy Meta runs until 31 December 2027.

Volume tiers and currencies

Businesses can unlock lower utility and authentication rates as their monthly volume grows; the tiers are specific to each market and category and reset every month. Meta describes these tiers for utility and authentication only. Meta publishes rate cards per market and region and bills in a list of currencies that includes USD, EUR, GBP, INR, BRL, AUD and others. For India, rates in rupees, tiers and the INR billing deadline are detailed in WhatsApp Business API pricing in India.

How to estimate your WhatsApp bill

Rates change, so check Meta's current rate card before you budget; the method stays the same:

1. List the messages your business sends first: reminders, confirmations, promotions, codes.
2. Give each one its category: marketing, utility or authentication.
3. Count them per month and per country of your customers' phone numbers.
4. Multiply by the rate of that category and country on Meta's current rate card, applying the volume tier you reach for utility and authentication.
5. Count your replies inside customer service windows as well: the first 1,000 a month per business number are free, the rest are charged at the service rate of each country.

What running WhatsApp agents taught us

• Design for the window. An agent that answers while the customer is still in the conversation can use free-form replies, free within the monthly service tier; the same answer a day later needs an approved, paid template.
• Utility, not marketing, where it is true. A booking confirmation is a utility message, billed at the utility rate rather than the marketing one. Categorise honestly — Meta reviews templates.
• Submit templates early. Approval takes time. A reminder flow cannot go live until its templates are approved, so they are the first thing we submit in a project.
• Consent comes first. Meta requires businesses to “obtain opt-in permission from the recipient confirming that they wish to receive subsequent messages or calls” from them. So we design the opt-in into the customer record from the start, not as an afterthought.