A small business in Vietnam usually runs on a pile of tools. Customers write on the website, in Zalo, on the Facebook page and in the app, each in its own tab. Bank transfers are matched to orders by hand, and someone types up e-invoices at the end of the day.
Ha Tang (Hạ Tầng in Vietnamese) puts that work in one place, with AI doing the repetitive part. It is built by Sota Labs, the products unit of SotaTek, and it is the platform under SotaTek's own products, including Hocdi.ai and tatca.ai. This article introduces Ha Tang, its main modules, who it is for and how to get started.
1. What Is Ha Tang?
Ha Tang is a business platform that joins customer support, sales, payments and invoicing into one flow. A customer writes on any channel, the AI assistant answers or a person takes over, the order is drafted in the chat, a VietQR payment is matched to it automatically, and the e-invoice is issued when the money arrives.
It is made of modules a business turns on as it needs them:
- Customer Support: one inbox for every channel, with an AI assistant.
- Products and orders: a catalog the AI and agents sell from inside the chat.
- Payments: VietQR bank transfers matched to orders, paid straight into the business's own account.
- E-invoices and accounting: invoices issued from paid orders, and books that follow the cash.
- Email: sending and receiving from the business's own domains.
Ha Tang serves two kinds of users. Shop owners, support teams and accountants work in the dashboard and the apps. Developers connect their own website or app through the API, SDKs and an MCP server for AI coding agents.
2. Why SotaTek Built Ha Tang
SotaTek has spent a decade building software for clients in 25 countries. When Sota Labs started building SotaTek's own consumer products, each one needed the same back office: support on many channels, payments by bank transfer, e-invoices, and transactional email.
In Vietnam that back office is harder than it looks:
- Customers spread across channels. Zalo, Facebook, TikTok and the website each have their own inbox, and the same customer appears as a stranger in each one.
- Payments arrive as bank transfers. Someone has to read the transfer note, find the order and confirm it, often late at night.
- Every sale needs an e-invoice. Issuing it by hand from a separate tool is slow and easy to miss.
Rather than stitch together a different vendor for each job, Sota Labs built one platform that does all of them on the same customer record, and opened it to other businesses as Ha Tang.
3. Key Features of Ha Tang
3.1. One Inbox for Every Channel
Messages from the website widget, the business's own mobile app, email, Zalo OA, personal Zalo, Facebook Messenger, Instagram, TikTok and TikTok Shop, WhatsApp, Telegram, LINE and X arrive in one shared inbox. The same customer is one profile across all of them, so an agent sees the whole history wherever the customer wrote.
Agents can assign conversations, leave internal notes, set reminders and schedule messages. The profile shows what the customer looked at before they wrote and what they bought after, so the team answers with context instead of asking again.
3.2. An AI Assistant That Learns from the Team
The AI assistant answers from the business's own knowledge: articles the team writes, pages of its website that Ha Tang reads and keeps up to date, and the product catalog with real prices. It can be the first responder, a draft writer for agents, or off, and it hands the conversation to a person with a summary when it can't help.
When an agent writes a better answer, one click teaches it to the AI. Questions the AI could not answer are collected in a list, so the team fills the gaps once instead of answering the same question every day.
3.3. Selling Inside the Conversation
Products, orders and payments live in the chat. The AI and agents send product cards, draft an order for the customer to confirm, and send a VietQR code for that order without leaving the conversation.
3.4. VietQR Payments Matched to Orders
Customers pay by scanning a VietQR code in their banking app, and the money goes straight into the business's own bank account, not a wallet in between. Ha Tang matches each incoming transfer to its order and marks the order paid, so nobody reads bank statements to confirm orders.
3.5. E-invoices and Accounting
When an order is paid, Ha Tang issues the e-invoice through the business's e-invoice provider. A reconciliation screen compares the money that arrived with the invoices issued and lists what is still missing, and every morning owners get an email about yesterday's money that still has no invoice.
3.6. Email on the Business's Own Domain
Ha Tang sends transactional and marketing email from the business's verified domains, with templates, broadcasts and automations. It also receives mail for the domain: support@ lands in the support inbox next to chat, and email groups forward team@ or sales@ to everyone's personal mailbox without paying for a seat per address.
4. Built for Developers and AI Coding Agents
The core of the platform is also an API, so a business can run Ha Tang behind its own website or app:
- Email API: a Resend-compatible POST /emails, an SMTP relay, React Email templates, inbound email as webhooks, and email groups.
- SDKs: the web chat widget, React and Next.js, React Native, Flutter, iOS (Swift), Android (Kotlin), Node.js, Python and a WordPress plugin.
- Webhooks: signed events for email, conversations, orders and payments.
- Docs for machines as well as people: every page of the developer hub is also served as Markdown, with an llms.txt index and an OpenAPI 3.1 spec.
- An MCP server (@hatang/mcp) lets AI coding agents such as Claude Code, Cursor and VS Code search the docs and call the API, with a read-only mode. Agent rules ship inside the npm packages, so an agent writes the integration the right way the first time.
A developer who builds a shop with an AI coding agent can add live chat, an AI assistant and VietQR checkout by asking the agent, and the agent reads the real docs instead of guessing field names.
5. Support Inside Your App, and on the Go
With the mobile SDKs, customers get help without leaving the business's own app. In the tatca.ai app, a user asks which monthly plans exist; the AI assistant answers with the real prices from the catalog and sends a product card with View and Buy buttons, then compares two plans when asked.
Agents are not tied to a desk either. Ha Tang has native apps for iPhone, Android and Mac, on the App Store, Google Play and the Mac App Store, with push notifications for new messages. From the phone an agent replies, sends a product or a payment, assigns a conversation and sees the customer's profile, the same as in the browser.
6. Who Uses Ha Tang
Ha Tang runs the back office of SotaTek's own products before it runs anyone else's.
- tatca.ai, an AI platform with more than 500,000 users on the web, iOS and Android, runs its support inbox, AI first responder, email, VietQR payments and invoicing on Ha Tang. Its AI assistant answers questions about plans and prices from a catalog of more than 30 products, and purchases from the web and the app stores sync to each customer's profile. The full story is in the tatca.ai case study.
- Hocdi.ai, the AI tutoring platform, uses Ha Tang for in-app support with an AI assistant that knows its course catalog.
The platform is built for the same kind of business outside SotaTek: online shops, education and subscription products, and service companies that sell and support customers in Vietnam.
7. How to Get Started
- Create a free account at hatang.dev. No card is needed.
- Connect a first channel, usually the website widget or Zalo OA.
- Add a few knowledge articles and the product catalog, then switch the AI assistant on.
- Link a bank account to take VietQR payments, and an e-invoice provider when you are ready to invoice.
- Developers can start from the developer hub or the Next.js starter.
Pricing is per module, in VND, with a free plan to start. Step-by-step guides are in the help center.
Conclusion
Ha Tang gives a business one place to answer customers on every channel, sell in the conversation, get paid by VietQR and issue e-invoices, with AI taking the repetitive work. It grew out of what SotaTek's own products needed, and it now runs products with hundreds of thousands of users.
To try it, visit hatang.dev. To talk to the team about a larger rollout, write to [email protected].
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