Zalo or WhatsApp for Customer Service in Vietnam, and Where Can an AI Agent Help?

Short answer: use both, for different customers. Zalo is widely used in Vietnam and ThinnestAI does not integrate with it, so our agent cannot answer Zalo Official Account messages. WhatsApp is the stronger fit for overseas guests, export buyers and expatriates, and there the same agent answers on WhatsApp, website chat and the phone with one memory of each customer. If nearly all your customers write to you on Zalo, we are not the right tool for that channel today.

How is Zalo used by businesses, and what do we know about its reach?

Zalo is a Vietnamese messaging app, and Zalo Official Accounts (OA) are how many Vietnamese brands talk to customers. Reports we read on 25 October 2026 describe Zalo as the most-used messaging tool in Vietnam, with Zalo's own figures for the first half of 2025 citing 78.3 million monthly active users (as reported by Brands Vietnam, not verified by us). We found no reliable, independent figure for how business customers split between Zalo and WhatsApp, so work out your own split from your inbox before you decide.

Where does WhatsApp fit in Vietnam?

WhatsApp Business is available in Vietnam, and vendor guides describe its use as mostly for international communication: tourism, export and overseas buyers. That is a vendor view, not a measurement. In practice the question is simple: which channel do your customers use to reach you? A hotel in Da Nang with guests from Europe and Australia will have many WhatsApp requests. A neighbourhood shop in Hanoi with local customers will have few.

What can the agent do on WhatsApp?

• Reply in 37 languages. Vietnamese and English are among them. Mandarin is not, and neither is Zalo.
• Answer from your knowledge base: rooms, treatments, product details, opening times, directions.
• Send templates for confirmations and reminders outside the 24-hour window. Meta reviews templates before you can use them.
• Hand over to your team through a shared inbox.
• Remember the customer across channels. A guest who phoned yesterday and writes today on WhatsApp is recognised by phone number; the agent says they have spoken before but withholds what was said until the person verifies.

What are the rules for messaging people on WhatsApp?

Meta's WhatsApp Business Messaging Policy (last updated 23 September 2026) says you may message only people who have given you their number and opted in to hear from you, and that you must respect requests to block or opt out. You are responsible for how you collect the opt-in. Vietnam has its own advertising-message rules; see our Vietnam rules guide. We do not claim that a WhatsApp opt-in satisfies Vietnamese law, so ask your adviser.

What if my customers are mostly on Zalo?

Then split the work. Keep Zalo for your team, let the phone agent catch the calls you miss, and put a WhatsApp number on your website, booking page and Google profile so that overseas customers have a channel the agent can answer. You can also add website chat. We do not offer a Zalo connection, and we will not promise one: if you need it, write to hello@thinnest.ai and tell us what you would use it for, but expect no date.

Does it matter which channel the customer chose first?

Yes, in one respect: answer on the channel they wrote on. A guest who wrote on WhatsApp should get the reply there, not a phone call you were not asked to make. If a customer asks for a call, the phone agent can do it, inside hours you set and with an opening line that says who is calling. Keep a note of how the person asked to be contacted, because the Vietnamese consent and advertising rules, and Meta's opt-in rule, all turn on what the person agreed to. The agent does not store proof of consent for you, so keep your own record in your booking system or spreadsheet.

What do I need to start?

1. Write down where your last fifty enquiries came from.
2. Connect the WhatsApp Business API inside the platform, where the agent's templates, broadcasts and inbox live.
3. Load your website and price list into the knowledge base.
4. Write the handover rule: which messages go to a person.

The Vietnam page has the languages, numbers and billing; see the WhatsApp AI agent and WhatsApp Business API pages, and the AI receptionist for calls.