LINE chatbot that answers with Claude

LINE chatbot that answers with Claude

An n8n workflow that connects a LINE Official Account to Claude. LINE sends each message to a webhook, the workflow pulls out
the first text message, Claude writes a short reply in the same language, and the workflow sends it back through LINE's reply
API.

What is inside

• workflow.json: the workflow as n8n exports it, five nodes, none of them a sticky note. It holds no credential.
• README.md: these notes.

What we changed from the original copy

• Extract Message read the call as $input.first().json. A Webhook node hands over headers, params, query and body,
  so the events list was never found and the bot never replied. It now reads $input.first().json.body.
• Its first comment said it validated the LINE signature. The code never did, so the comment now says it does not.
• The Claude request and the LINE reply placed raw text between quotes in their JSON bodies, so any message or answer with a
  line break or a quote broke them. Each value now goes through JSON.stringify(...).slice(1, -1).
• The webhook ID is gone.
• Nothing else. The key, the token and the model are the file's own.

Before you start

• An n8n instance reachable from the internet over HTTPS, on n8n Cloud or your own server. LINE's webhook URL must use HTTPS with a
  certificate from a widely trusted authority, and self-signed ones are refused.
• A LINE Official Account with the Messaging API turned on, and its channel access token.
• An Anthropic API key.
• A way to set two environment variables on the n8n server, or a willingness to type the values into the nodes.

Set it up

1. In n8n, create a workflow, open its menu and choose Import from File. Pick workflow.json.
2. Give n8n the two secrets. The file reads them as {{ $env.ANTHROPIC_API_KEY }} in the x-api-key header of Ask Claude,
   and as Bearer {{ $env.LINE_CHANNEL_ACCESS_TOKEN }} in the Authorization header of Reply via LINE. Set both as
   environment variables on the server, or replace each expression with the value itself.
3. Save and publish the workflow. Copy the production address from LINE Webhook.
4. In the LINE Developers console, paste that address as the channel's webhook URL, click Verify and turn Use webhook on.
5. Send your account a text message and wait for Claude's reply.

How a run goes

1. LINE Webhook (Webhook 2) takes LINE's POST and passes the call to Extract Message and to Return 200.
2. Extract Message (Code) looks through body.events for the first event that is a text message, and keeps userId,
   replyToken and the text. Stickers, images and other events end that branch here.
3. Ask Claude posts the text to https://api.anthropic.com/v1/messages with claude-opus-4-5, up to 500 tokens and a system
   line that asks for a short reply in whatever language the person wrote.
4. Reply via LINE posts Claude's answer to https://api.line.me/v2/bot/message/reply with the reply token.
5. Return 200 answers LINE with OK. n8n finishes the upper branch first, so this comes last.

Change the look

• The bot's character: the system line in Ask Claude.
• The model and the length: model and max_tokens in the same node.
• What it answers: the Code node. Add more event types, or keep earlier messages by userId.

Good to know

• Anthropic's deprecations page, read on 12 November 2026, lists claude-opus-4-5 (claude-opus-4-5-20251101 there) as active,
  with a retirement date no sooner than 24 November 2026 and no replacement named yet. Check the page before relying on it,
  or change model in Ask Claude to a newer Claude model.
• Each message is answered alone. Claude sees only the one message, with no earlier turns.
• LINE signs every webhook with an x-line-signature header. Nothing in this workflow checks it, so anyone who finds the
  address can send fake events, and each text one spends your Anthropic key. LINE's documentation says to verify the signature
  before processing an event.
• Return 200 runs after the reply branch, so LINE waits for Claude. When the Claude call or the reply fails, the run stops before
  Return 200 and LINE does not get its OK.
• The workflow answers only the first text event in a call.
• Reply messages do not count toward a LINE plan's monthly message count, according to LINE's pricing page, read on
  12 November 2026.
• A LINE reply holds up to five message objects. This one sends a single text.
• The message goes to Anthropic, and the answer goes back through LINE.