Reply to Instagram and WhatsApp DMs With an AI Agent

The short answer: if your DMs are mostly questions about products, delivery and orders and one or two people answer them, Chatfuel's Business plan at $20 a month puts one AI agent on Instagram and WhatsApp with a shared inbox and unlimited teammates (Chatfuel plans); when several teams route chats and sync a CRM, respond.io's Growth plan at $199 a month for 1,000 monthly active contacts is the first of its plans with AI Agents (respond.io pricing, both checked on 26 October 2026). Instagram is free to use (respond.io's Instagram overview); WhatsApp is not. After the 1,000 free service messages per number each month, Meta charges $0.05 per reply to a Dutch number, so 2,600 replies in a month cost (2,600 - 1,000) x $0.05 = $80 (Meta pricing).

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The job: a customer asks about a size under a reel, or sends "is this in stock" on WhatsApp at midnight. The agent answers inside the rules each channel sets, a person takes refunds and anything Instagram only lets humans answer, and offers go out only as approved templates to people who said yes. The single-tool walkthroughs are How to use Chatfuel, How to use respond.io and How to use Manychat, and the plans sit in the Chatfuel, respond.io and Manychat entries.

Settle three things first:

1. The message bill. Meta bills a business per delivered message, by category and country, and never for messages customers send (Meta pricing). For example, one promotion to 1,500 opted-in Dutch contacts at Meta's marketing rate of $0.1597 costs 1,500 x $0.1597 = $239.55. respond.io adds nothing on top of Meta's fees (pricing calculator); Manychat's own card lists $0.1836 for the same message (Manychat pricing guide).
2. The consent you already hold. Meta lets a business contact someone on WhatsApp only when that person gave the number and an opt-in confirming they want messages from the business, which has to be named (opt-in guide). Find where yours lives today: a checkout box, a form field, a reply in an earlier chat. Contacts without one stay out of every template send.
3. The baseline. Four weeks of median first-reply time per channel, DMs per week, and orders from people who messaged before buying. Write them down before the agent answers anything.

The rules every step has to fit

WhatsApp. Free-form replies are allowed inside the 24-hour customer service window, which opens and resets with each message from the customer; outside it, only approved templates. Automation inside the window is allowed if prompt, clear escalation paths exist, and an in-chat transfer to a human agent is the first one the policy lists (WhatsApp Business Messaging Policy).

Templates. Each one is marketing, utility or authentication. Utility has to be non-promotional and either tied to the customer's own order, account or request, or essential to them, and a template mixing an order update with an offer counts as marketing (template categorization).

Instagram. Most customer actions open a 24-hour standard window, up to 7 days after a Click-to-Direct ad. A human agent who needs longer can tag the reply for a separate 7-day Human Agent window. Meta's docs describe passing a thread from the automated experience to a human inbox, and, where the law requires it, a line at the start saying the person is talking to an automated service (Instagram messaging docs).

EU law. Article 50 of the AI Act wants people told they are dealing with an AI system by the first interaction, unless it is obvious (Regulation (EU) 2024/1689 on EUR-Lex); How to use Trengo shows the notice in a WhatsApp agent. Article 13(1) of the ePrivacy Directive allows direct marketing by electronic mail only with prior consent, and Article 2(h) defines electronic mail as any text, voice, sound or image message sent over a public network that can be stored until the recipient collects it (consolidated text on EUR-Lex). Ask counsel how your country applies that to WhatsApp, and whether the existing-customer exception in Article 13(2) covers offers to people who bought from you.

The workflow, message by message

1. The trigger: a message lands. Both channels arrive in one inbox. Chatfuel's live chat takes WhatsApp, Instagram, Messenger, TikTok and website chats, plus post comments (live chat page); respond.io connects an Instagram Business Account to its inbox (Instagram overview) and handles WhatsApp's window and templates in the same place (inbound guide).

2. The agent step: read, decide, reply. In respond.io, build the agent from the Receptionist, Sales Agent or Support Agent template; choosing a template does not publish it, and the Assign to agent or team skill hands a chat over with context (AI agent guide). The agent reads the message, your knowledge sources and at most the 20 most recent messages in the thread, and it cannot see internal comments (known limitations), so a note your team left is invisible to it. Write into its instructions that the first reply says it is an AI assistant and how to reach a person.

3. The human check: three decisions stay with people. Refunds, complaints and payment questions go to the team by rule; in Chatfuel the AI passes such a chat on with a short summary and stops replying (live chat page). An Instagram thread whose last customer message is more than 24 hours old belongs to a person: respond.io tags those messages HUMAN_AGENT and cannot send after 7 days (Instagram overview), and Manychat's help centre is explicit that automated messages are not allowed in the 7-day window (Manychat windows article). And a person writes each template, picks its category and checks the list before anything is sent.

4. Templates restart a quiet WhatsApp chat. Once 24 hours have passed since the customer's last message, only a template reopens the conversation (respond.io inbound guide). Chatfuel sends approved templates from live chat or to a segment, and its AI answers whatever comes back (templates page). An order update goes as utility; anything with an offer in it is marketing and goes only to contacts whose opt-in you can show.

5. The weekly review, done by an agent. Chatfuel's MCP server lets Claude or ChatGPT read up to 100 recent chats and list the ones left unanswered and the questions the FAQ misses, with a Read-only switch at sign-in (MCP page). A person reads the list and writes the missing answers; the assistant adds them only once given.

6. The output. Each conversation ends answered, handed over with context, or closed with a template a person approved. Opt-in date and source sit on the contact, which is the record you need when someone asks.

The free version

The WhatsApp Business app is free to download and use, with a mix of free and paid features (App Store listing); it greets new customers, sends away messages outside business hours and keeps quick replies and labels (Business app features). Write a quick reply for each answer on your delivery and returns pages, and answer Instagram by hand in the Instagram app. Manychat's Free plan adds up to 4 live Instagram automations for 25 Active Contacts a month, with no WhatsApp and a "Powered by Manychat" message on first contact (Free plan).

Up to a few dozen messages a day, quick replies written by the person who knows the policies are enough on their own. The paid tools add three things: an agent that answers at midnight, one inbox for both channels, and handover rules that run without anyone watching.

What it costs a month

Checked on 26 October 2026, in USD on monthly billing, on Chatfuel's plans article and pricing page, the respond.io pricing page, Manychat's Pro plan and AI Replies articles, and Meta's pricing page with its USD rate card. Manychat's own pricing page blocked automated reading that day, so its figures come from its help centre.

How to know it worked

• The measure. Median first-reply time per channel, and the share of agent-closed chats that a reviewer, reading 20 a week, would sign off as correct.
• The baseline. The four weeks you wrote down before launch: reply time, DMs per week and orders from people who messaged first.
• A holdout. None of these tools assigns customers to an agent at random, so alternate by week: the agent takes new chats in weeks one and three, people take them in weeks two and four. It is cruder than a random split; keep promotions out of those four weeks.
• The guardrails. STOP replies and blocks after each template send. Meta rate-limits a business whose quality stays low (opt-in guide), so a rise there costs reach before it costs anything else.

Who gains from a template's category

Meta prices a marketing message to a Dutch number at $0.1597 and a utility message at $0.05, and its categorization rules count any template that mixes an order update with an offer as marketing (template categorization, Meta pricing). Adding a discount line to a shipping update looks free in the editor and moves the message into the category that earns Meta more than three times as much. Keep the two apart.

FAQ

Can the AI agent message customers first on WhatsApp?

Only with an approved template, and a marketing template only to contacts who opted in to messages from your business. Free-form messages, including the agent's replies, need the 24-hour window the customer opened (WhatsApp Business Messaging Policy).

Does the agent count against Meta's free 1,000 service messages?

Yes. Meta counts service messages from the business whether a person or an AI wrote them, and charges from the 1,001st each month per number (Meta pricing). Agents that answer in one message instead of four use the allowance more slowly.

What does the agent do with an Instagram question after a day?

Nothing. Once the standard 24-hour window has closed, the reply has to come from a person, under the Human Agent tag, within 7 days of the customer's last message (Instagram messaging docs). Route those threads to the team in the agent's rules, so the customer hears from someone the next morning.