LINE chatbot guide: 3 ways to build one with AI agents (2026)
TL; DR: Quick Summary
- A LINE chatbot answers customers inside your LINE Official Account, and you can code one, use keyword replies or run AI agents.
- LINE has 54 million monthly users in Thailand and 22 million in Taiwan, per LY Corporation, and replies to them don't use your quota.
- Since September 4, 2024, developers enable the Messaging API from LINE Official Account Manager instead of the LINE Developers Console.
- Keyword auto-replies break when customers phrase questions their own way, while AI agents understand off-script questions and take action.
- Choose a no-code AI agent platform if you have no developers, and the Messaging API only if you want to own the code.
In Japan, Thailand and Taiwan, many customers message businesses on LINE. Their questions don't stop when your team logs off.
A chatbot can answer them. The real choice is how much of the conversation you want it to handle.
What is a LINE chatbot?
A LINE chatbot is a program connected to your LINE Official Account that reads incoming messages and replies without a person typing. LINE sends each message to your bot through a webhook, and the bot answers through the Messaging API. You can build one with code, set up keyword replies or connect AI agents.
LY Corporation reported 193 million monthly LINE users worldwide in March 2026, including 100 million in Japan, 54 million in Thailand and 22 million in Taiwan.
Why put a chatbot on LINE?
A chatbot answers the questions that arrive when your team is offline, and on LINE those answers don't cost extra. LINE's Messaging API pricing page lists reply messages as not counted toward your monthly limit. Push, multicast, broadcast and narrowcast messages are counted.
That changes the math. Answering every customer quickly never pushes you onto a bigger LINE plan.
Other reasons teams add one:
Customers message after hours. A late-night browse turns into a question at 11 p.m.
Your team stops repeating itself. Price, stock, delivery and booking questions come up again and again.
Every chat becomes data. Each conversation adds to the customer's profile, so the next message can be more relevant.
How do you build a LINE bot with the Messaging API?
The Messaging API gives you full control, but you need a developer and a server. You enable the API from your LINE Official Account, issue a channel access token, set an HTTPS webhook URL and write the bot's logic yourself. Choose this route only if you want to own the code and keep maintaining it.
The short version, from LINE's getting started guide:
Enable the Messaging API in LINE Official Account Manager. Since September 4, 2024, you can't create a Messaging API channel directly in the LINE Developers Console.
Choose a provider carefully. Once a provider manages your LINE Official Account, you can't change or de-assign it.
Issue a channel access token so your bot can call the API.
Set your webhook URL. It must use HTTPS, and self-signed certificates aren't allowed.
Turn off greeting and auto-reply messages if your bot handles replies, so customers don't get two answers.
For token types, webhook events and code samples, read our full LINE Messaging API guide.
To sketch a conversation before writing code, LINE Developers offers LINE Bot Designer, a free prototyping tool that needs no programming.
The build is the easy part. Designing conversations, connecting product data and handling questions you didn't plan for is where most of the work sits.
Can you use LINE Official Account Manager auto-replies instead?
Yes, for simple cases. LINE Official Account Manager has two free, no-code tools: a greeting message for new friends and auto-replies triggered by keywords like "hours" or "price". They work for opening hours and a short FAQ, but break when customers phrase things their own way or ask two things at once.
You also can't run these auto-replies alongside your own Messaging API bot without risking double replies.
What is LINE's AI Chatbot (beta)?
In Thailand, LINE Official Account has an AI Chatbot (beta) that picks the best answer from a Q&A list you register. It can build that list from PDFs and images, and it copes with some differences in wording. You need a Chat Pro subscription to turn it on.
It still answers from a fixed list, and keyword auto-replies take priority over it. It doesn't qualify leads, take actions or hand off with a summary.
How do you build a LINE AI agent with SleekFlow?
You connect your LINE Official Account to SleekFlow, then build AI agents in AgentFlow without code. The agents read your website and documents, answer customers on LINE at any hour and pass chats to your team when a person is needed. There's no server to run and no token to renew.
How do you connect LINE to SleekFlow?
These steps follow SleekFlow's Help Center guide:
In LINE Official Account Manager, go to Settings, then Messaging API, and click Enable Messaging API.
In SleekFlow, open Channels, click Connect on LINE Business and copy the Webhook URL.
Paste the Webhook URL into LINE Official Account Manager, save it and update your response settings.
Copy your Channel ID, Channel Secret and Basic ID (it looks like @XXXXXXXX) into SleekFlow, name the channel and click Connect.
What can a LINE AI agent do that a chatbot can't?
SleekFlow's LINE integration lets you deploy AI agents that answer, qualify and hand off. Built in AgentFlow, they:
Handle off-script questions. Customers don't hit "Sorry, I didn't understand."
Collect lead details. The agent asks about needs and timing, then routes the lead to the right next step.
Stay current. Agents read your website, so you don't rebuild flows each time a price changes.
Follow your playbook. You train them on your SOPs and product information.
Hand off with context. A person picks up the chat with a summary, and the customer doesn't repeat anything.
How Checkmob qualifies leads with AI agents
Checkmob, a field sales software company in Brazil, used to qualify every lead by hand. Its reps answered the same questions over and over and booked demos manually.
Now AgentFlow handles first contact, qualification and demo booking on WhatsApp, and syncs each lead to the CRM. "AgentFlow does all of that automatically," says Andre Zacarias, Head of Sales at Checkmob.
70% reduction in response time
20% growth in qualified demo bookings
The same agents run on LINE once your account is connected.
LINE chatbot best practices
Whichever route you pick, these habits make any LINE bot more useful:
Give people a reason to reply. "Ask us anything about sizes" beats "Thanks for adding us."
Add a Chat with us button to your rich menu. It's the easiest way into a conversation.
Use quick replies for common choices like branch, budget or product type.
Reply in your customers' language, such as Japanese, Thai or Traditional Chinese.
Always offer a person, and pass the chat over with its history.
Test with real questions. Run 20 to 30 real customer messages through the bot before launch.
Review chats every week and update the bot's knowledge where it got things wrong.
Start for free!
Grow your revenue and turn chats into conversions with AI agents. Try SleekFlow for free.
