How to Build a WhatsApp Business Auto-Reply with AI

Key takeaways

• Start with WhatsApp Business's free built-in tools: greeting messages, away messages and quick replies. They're not AI, but they handle most "how much?" and "are you open?" messages.
• For real AI replies, Meta's own Business AI agent is rolling out globally since June 2026. It can draft replies for you to approve or answer customers itself, and hand over to you when needed.
• For full control, build a bot on the WhatsApp Business Platform (API) through a provider like Wati, respond.io or Twilio, connected to an AI model.
• From 1 October 2026, Meta charges for service replies on the API beyond 1,000 free a month per number. In Nigeria, that's about $0.0101 (roughly ₦14) per message.
• Since 15 January 2026, Meta bans general-purpose AI chatbots on the WhatsApp API. Your bot must stick to your business: orders, products, bookings, support.

The quickest way to get AI replying on WhatsApp is Meta's Business AI agent, which is rolling out inside WhatsApp Business and can answer customers, suggest replies for you to approve, and hand chats back to you. If you need more control, build a bot on the WhatsApp Business Platform using a provider like Wati or respond.io connected to an AI model. Before either, set up the free greeting, away and quick-reply tools, because they cover a surprising amount for nothing.

Which approach should you use?

Approach	Cost	Setup effort	Best for
Built-in auto-replies (no AI)	Free	15 minutes	Every business, as a starting point
Meta Business AI agent	Not yet clear in the app; charged per token on the API	Low	Small businesses that want AI without building anything
Custom AI bot on the WhatsApp API	Meta's per-message fees + provider subscription + AI usage	Medium to high	Busier businesses, online stores, teams

Step 1: Set up the free auto-replies first

The WhatsApp Business app includes three tools that cost nothing. Find them under Settings → Business tools.

Greeting message. Sent automatically when someone messages you for the first time, or after a long gap. Use it to answer the obvious questions before they're asked:

Hi, thanks for messaging Ada's Kitchen! 🍲 Our menu and prices are in our Catalogue (tap the shop icon above). We deliver within Lekki, Ajah and VI from 11am to 8pm. Pay by transfer or card on delivery. What would you like to order?

Away message. Sent outside your business hours. Tell customers when you'll be back, and point them to your catalogue so they can decide in the meantime.

Quick replies. Saved answers you trigger by typing a shortcut, like /price, /delivery or /pay. They're not automatic, but they turn a two-minute typed reply into two seconds.

Also fill in your catalogue, business hours and address. Both people and AI tools pull from these.

Step 2: Turn on Meta's Business AI agent

In June 2026, Meta announced its AI business agent for WhatsApp Business was available globally, across iOS, Android and the Business Platform. According to WABetaInfo, it can answer customers in real time, handle several chats at once and reply outside business hours.

How it works:

• Set it up from the business tools page in WhatsApp Business. If you don't see it, update the app to the latest version.
• You can let it learn from your past chats so its tone matches yours, or let it learn over time.
• You refine it in a chat called "Your AI agent".
• You choose how much it does, chat by chat:
  • My reply: fully manual
  • Suggestions: the AI drafts, you decide whether to send
  • Agent: the AI replies on its own, and you can take over any time

Start with Suggestions. Read the drafts for a week or two. You'll quickly see where it gets things wrong, like delivery fees or stock, before customers do.

What does it cost? That's still unclear for the free app. Omnichat's August 2026 analysis says Meta plans to include the agent in some tiers of a WhatsApp Business Premium subscription, but hasn't published the details. On the Business Platform (API), Meta charges $2 per million tokens for agent replies since mid-2026, which Omnichat estimates at roughly $0.04 to $0.05 per reply.

Step 3 (optional): Build your own AI bot on the WhatsApp API

If you want full control, such as checking stock in your own system, creating orders, or replying in Pidgin or Swahili with your own instructions, you'll need the WhatsApp Business Platform, also called the WhatsApp API. You can't plug a custom AI into the free app.

What you'll need

1. A WhatsApp Business Solution Provider (BSP) such as Wati, respond.io or Twilio. They give you API access, a shared team inbox and, usually, a bot builder. Most also connect to Shopify or WooCommerce.
2. A phone number that isn't already registered on the WhatsApp or WhatsApp Business app, or you'll need to move it over.
3. An AI model. Many BSPs include AI features. Others let you connect your own model through their tools or through automation platforms like Make or Zapier.
4. Your business knowledge: prices, delivery areas and fees, payment methods, return policy and opening hours, written down clearly.

What it costs

There are three layers of cost:

1. Meta's messaging fees. Meta charges per delivered message from your business, at rates that vary by country and message type. Messages from customers are free. The important change is from 1 October 2026:

• Each number gets 1,000 free service messages a month. Replies beyond that are charged.
• Utility replies within the 24-hour window, which used to be free, are now charged.
• In Nigeria, Dubawa and Vanguard report about $0.0101 (roughly ₦14) per utility or service message and about $0.062 (roughly ₦84) per marketing message.
• Click-to-WhatsApp ads get a free window of up to seven days for replies to customers who message you from the ad.

None of this applies to the free WhatsApp Business app or to personal chats. Dubawa fact-checked viral claims that ordinary Nigerians would pay ₦14 per message and rated them misleading.

2. Your provider's subscription. BSPs charge their own monthly fees on top of Meta's. Most bill in US dollars, so you'll need a card that works abroad. Our guide to virtual dollar cards helps.

3. AI usage. If the AI isn't included in your plan, you'll pay for model usage separately.

Meta's 2026 rule: keep the bot about your business

Since 15 January 2026, Meta has banned general-purpose AI chatbots on the WhatsApp Business Platform, according to respond.io. Gulf News reported that the rule affects bots like ChatGPT's and Perplexity's on WhatsApp.

What's still allowed: business-focused bots for orders, support, bookings, delivery tracking, reminders and sales, where the AI supports your service rather than being the product itself. So instruct your bot to stay on topic and politely decline anything unrelated.

A ready-to-use AI prompt for your WhatsApp bot

Whichever tool you use, the instructions you give the AI matter more than the tool. Here's a starting point. Replace everything in brackets.

You are the WhatsApp assistant for [Business name], a [what you sell] business in [city].

Your job: answer customer questions about our products, prices, delivery and payment, and help them place orders.

Facts you can use (never invent others):
- Products and prices: [list, or "see the catalogue"]
- Delivery: [areas], [fees], [delivery times]
- Payment: [methods, e.g. bank transfer, card, M-Pesa Till number]
- Hours: [days and times]
- Returns: [policy]

Rules:
- Keep replies short and friendly. Use the customer's language: English, Pidgin, Swahili or [others].
- If you don't know something, say you'll check, and hand over to a human.
- Never confirm that a payment has been received. Say a team member will confirm.
- Never change prices, offer discounts or promise delivery dates that aren't listed above.
- Only talk about [Business name]. Politely decline unrelated questions.
- Hand over to a human when a customer is upset, asks for a refund, or asks for something custom.

Two rules in there deserve emphasis:

• Never let the AI confirm payments. Fake transfer screenshots and alerts are a common scam. A human, or your payment system, should confirm money has arrived before an order ships.
• Never let it invent prices. AI models will happily "remember" a price that's six months old. Keep your catalogue up to date, and tell the bot to use only what you've given it.

For more on replying in local languages, see our guide to AI customer support in local languages.

Test it before customers do

1. Message your own business number from a friend's phone and ask 20 real questions from your chat history.
2. Try to break it. Ask for a discount, ask about a product you don't sell, send a voice note, write in Pidgin or Swahili.
3. Check every price and fee it quotes.
4. Run in Suggestions mode first if you're using Meta's agent, or with a human reviewing replies if you've built your own.
5. Review chats weekly for the first month and update your instructions.

Which should you choose?

• Fewer than 20 chats a day: built-in greeting, away and quick replies. Add Meta's AI agent in Suggestions mode when it appears in your app.
• 20 to 200 chats a day, mostly the same questions: Meta's AI agent, with clear instructions and a human checking edge cases.
• An online store, a team handling chats, or a need to connect to stock or orders: a BSP like Wati or respond.io on the WhatsApp API, with a business-focused AI bot. Budget for Meta's per-message fees after 1,000 free service replies a month.