How to Send an AI Welcome Message When Someone Opens Your Viber Bot

First impressions matter. Viber fires a conversation_started event the moment a user opens your bot, before they type anything. Replying in that window with a friendly, on-brand greeting boosts subscription rates. Here you will craft that greeting with AI and return it the way Viber expects.

What you need

• A working Viber bot with a set webhook (see the Viber bot guide)
• The conversation_started event in your event_types list
• Node 18+ and an AI API key

Step 1: Add the event to your webhook

Re-run set_webhook with conversation_started added so Viber notifies you when a user opens the chat.

Step 2: Generate and return the greeting

When the event type is conversation_started, ask the model for a short welcome that fits your brand, then send it back directly in res.json. Use the user's name from the payload to make it personal.

app.post("/viber", async (req, res) => {
  if (req.body.event === "conversation_started") {
    const name = req.body.user?.name || "there";

    const out = await ai.chat.completions.create({
      model: "gpt-5-mini",
      messages: [
        {
          role: "system",
          content:
            "Write a one sentence warm welcome for a support bot. Address the user by name.",
        },
        { role: "user", content: `The user is named ${name}.` },
      ],
    });

    return res.json({
      type: "text",
      text: out.choices[0].message.content,
    });
  }

  res.sendStatus(200);
  // ... handle "message" events as before
});

Result

New users now get a personalized AI greeting the instant they open your bot, which nudges more of them to subscribe and start a real conversation.