WhatsApp Chat Bot
This example demonstrates how to create a WhatsApp chat bot using Mastra agents and workflows. The bot receives incoming WhatsApp messages via webhook, processes them through an AI agent, breaks responses into natural text messages, and sends them back via the WhatsApp Business API.
Prerequisites
This example requires a WhatsApp Business API setup and uses the anthropic
model. Add these environment variables to your .env
file:
ANTHROPIC_API_KEY=<your-anthropic-api-key>
WHATSAPP_VERIFY_TOKEN=<your-verify-token>
WHATSAPP_ACCESS_TOKEN=<your-whatsapp-access-token>
WHATSAPP_BUSINESS_PHONE_NUMBER_ID=<your-phone-number-id>
WHATSAPP_API_VERSION=v22.0
Creating the WhatsApp client
This client handles sending messages to users via the WhatsApp Business API.
// Simple WhatsApp Business API client for sending messages
interface SendMessageParams {
to: string;
message: string;
}
export async function sendWhatsAppMessage({ to, message }: SendMessageParams) {
// Get environment variables for WhatsApp API
const apiVersion = process.env.WHATSAPP_API_VERSION || "v22.0";
const phoneNumberId = process.env.WHATSAPP_BUSINESS_PHONE_NUMBER_ID;
const accessToken = process.env.WHATSAPP_ACCESS_TOKEN;
// Check if required environment variables are set
if (!phoneNumberId || !accessToken) {
return false;
}
// WhatsApp Business API endpoint
const url =
`https://graph.facebook.com/${apiVersion}/${phoneNumberId}/messages`;
// Message payload following WhatsApp API format
const payload = {
messaging_product: "whatsapp",
recipient_type: "individual",
to: to,
type: "text",
text: {
body: message,
},
};
try {
// Send message via WhatsApp Business API
const response = await fetch(url, {
method: "POST",
headers: {
"Content-Type": "application/json",
Authorization: `Bearer ${accessToken}`,
},
body: JSON.stringify(payload),
});
const result = await response.json();
if (response.ok) {
console.log(`✅ WhatsApp message sent to ${to}: "${message}"`);
return true;
} else {
console.error("❌ Failed to send WhatsApp message:", result);
return false;
}
} catch (error) {
console.error("❌ Error sending WhatsApp message:", error);
return false;
}
}
Creating the chat agent
This agent handles the main conversation logic with a friendly, conversational personality.
import { anthropic } from "@ai-sdk/anthropic";
import { Agent } from "@mastra/core/agent";
import { Memory } from "@mastra/memory";
import { LibSQLStore } from "@mastra/libsql";
export const chatAgent = new Agent({
name: "Chat Agent",
instructions: `
You are a helpful, friendly, and knowledgeable AI assistant that loves to chat with users via WhatsApp.
Your personality:
- Warm, approachable, and conversational
- Enthusiastic about helping with any topic
- Use a casual, friendly tone like you're chatting with a friend
- Be concise but informative
- Show genuine interest in the user's questions
Your capabilities:
- Answer questions on a wide variety of topics
- Provide helpful advice and suggestions
- Engage in casual conversation
- Help with problem-solving and creative tasks
- Explain complex topics in simple terms
Guidelines:
- Keep responses informative but not overwhelming
- Ask follow-up questions when appropriate
- Be encouraging and positive
- If you don't know something, admit it honestly
- Adapt your communication style to match the user's tone
- Remember this is WhatsApp, so keep it conversational and natural
Always aim to be helpful while maintaining a friendly, approachable conversation style.
`,
model: anthropic("claude-4-sonnet-20250514"),
memory: new Memory({
storage: new LibSQLStore({
url: "file:../mastra.db",
}),
}),
});
Creating the text message agent
This agent converts longer responses into natural, bite-sized text messages suitable for WhatsApp.
import { anthropic } from "@ai-sdk/anthropic";
import { Agent } from "@mastra/core/agent";
import { Memory } from "@mastra/memory";
import { LibSQLStore } from "@mastra/libsql";
export const textMessageAgent = new Agent({
name: "Text Message Agent",
instructions: `
You are a text message converter that takes formal or lengthy text and breaks it down into natural, casual text messages.
Your job is to:
- Convert any input text into 5-8 short, casual text messages
- Each message should be 1-2 sentences maximum
- Use natural, friendly texting language (contractions, casual tone)
- Maintain all the important information from the original text
- Make it feel like you're texting a friend
- Use appropriate emojis sparingly to add personality
- Keep the conversational flow logical and easy to follow
Think of it like you're explaining something exciting to a friend via text - break it into bite-sized, engaging messages that don't overwhelm them with a long paragraph.
Always return exactly 5-8 messages in the messages array.
`,
model: anthropic("claude-4-sonnet-20250514"),
memory: new Memory({
storage: new LibSQLStore({
url: "file:../mastra.db",
}),
}),
});
Creating the chat workflow
This workflow orchestrates the entire chat process: generating a response, breaking it into messages, and sending them via WhatsApp.
import { createStep, createWorkflow } from "@mastra/core/workflows";
import { z } from "zod";
import { sendWhatsAppMessage } from "../../whatsapp-client";
const respondToMessage = createStep({
id: "respond-to-message",
description: "Generate response to user message",
inputSchema: z.object({ userMessage: z.string() }),
outputSchema: z.object({ response: z.string() }),
execute: async ({ inputData, mastra }) => {
const agent = mastra?.getAgent("chatAgent");
if (!agent) {
throw new Error("Chat agent not found");
}
const response = await agent.generateVNext(
[{ role: "user", content: inputData.userMessage }],
);
return { response: response.text };
},
});
const breakIntoMessages = createStep({
id: "break-into-messages",
description: "Breaks response into text messages",
inputSchema: z.object({ prompt: z.string() }),
outputSchema: z.object({ messages: z.array(z.string()) }),
execute: async ({ inputData, mastra }) => {
const agent = mastra?.getAgent("textMessageAgent");
if (!agent) {
throw new Error("Text Message agent not found");
}
const response = await agent.generateVNext(
[{ role: "user", content: inputData.prompt }],
{
structuredOutput: {
schema: z.object({
messages: z.array(z.string()),
}),
},
},
);
if (!response.object) throw new Error("Error generating messages");
return response.object;
},
});
const sendMessages = createStep({
id: "send-messages",
description: "Sends text messages via WhatsApp",
inputSchema: z.object({
messages: z.array(z.string()),
userPhone: z.string(),
}),
outputSchema: z.object({ sentCount: z.number() }),
execute: async ({ inputData }) => {
const { messages, userPhone } = inputData;
console.log(
`\n🔥 Sending ${messages.length} WhatsApp messages to ${userPhone}...`,
);
let sentCount = 0;
// Send each message with a small delay for natural flow
for (let i = 0; i < messages.length; i++) {
const success = await sendWhatsAppMessage({
to: userPhone,
message: messages[i],
});
if (success) {
sentCount++;
}
// Add delay between messages for natural texting rhythm
if (i < messages.length - 1) {
await new Promise((resolve) => setTimeout(resolve, 1000));
}
}
console.log(
`\n✅ Successfully sent ${sentCount}/${messages.length} WhatsApp messages\n`,
);
return { sentCount };
},
});
export const chatWorkflow = createWorkflow({
id: "chat-workflow",
inputSchema: z.object({ userMessage: z.string() }),
outputSchema: z.object({ sentCount: z.number() }),
})
.then(respondToMessage)
.map(async ({ inputData }) => ({
prompt:
`Break this AI response into 3-8 casual, friendly text messages that feel natural for WhatsApp conversation:\n\n${inputData.response}`,
}))
.then(breakIntoMessages)
.map(async ({ inputData, getInitData }) => {
// Parse the original stringified input to get user phone
const initData = getInitData();
const webhookData = JSON.parse(initData.userMessage);
const userPhone =
webhookData.entry?.[0]?.changes?.[0]?.value?.messages?.[0]?.from ||
"unknown";
return {
messages: inputData.messages,
userPhone,
};
})
.then(sendMessages);
chatWorkflow.commit();
Setting up Mastra configuration
Configure your Mastra instance with the agents, workflow, and WhatsApp webhook endpoints.
import { Mastra } from "@mastra/core/mastra";
import { registerApiRoute } from "@mastra/core/server";
import { PinoLogger } from "@mastra/loggers";
import { LibSQLStore } from "@mastra/libsql";
import { chatWorkflow } from "./workflows/chat-workflow";
import { textMessageAgent } from "./agents/text-message-agent";
import { chatAgent } from "./agents/chat-agent";
export const mastra = new Mastra({
workflows: { chatWorkflow },
agents: { textMessageAgent, chatAgent },
storage: new LibSQLStore({
url: ":memory:",
}),
logger: new PinoLogger({
name: "Mastra",
level: "info",
}),
server: {
apiRoutes: [
registerApiRoute("/whatsapp", {
method: "GET",
handler: async (c) => {
const verifyToken = process.env.WHATSAPP_VERIFY_TOKEN;
const {
"hub.mode": mode,
"hub.challenge": challenge,
"hub.verify_token": token,
} = c.req.query();
if (mode === "subscribe" && token === verifyToken) {
return c.text(challenge, 200);
} else {
return c.status(403);
}
},
}),
registerApiRoute("/whatsapp", {
method: "POST",
handler: async (c) => {
const mastra = c.get("mastra");
const chatWorkflow = mastra.getWorkflow("chatWorkflow");
const body = await c.req.json();
const workflowRun = await chatWorkflow.createRunAsync();
const runResult = await workflowRun.start({
inputData: { userMessage: JSON.stringify(body) },
});
return c.json(runResult);
},
}),
],
},
});
Testing the chat bot
You can test the chat bot locally by simulating a WhatsApp webhook payload.
import "dotenv/config";
import { mastra } from "./mastra";
// Simulate a WhatsApp webhook payload
const mockWebhookData = {
entry: [
{
changes: [
{
value: {
messages: [
{
from: "1234567890", // Test phone number
text: {
body: "Hello! How are you today?"
}
}
]
}
}
]
}
]
};
const workflow = mastra.getWorkflow("chatWorkflow");
const workflowRun = await workflow.createRunAsync();
const result = await workflowRun.start({
inputData: { userMessage: JSON.stringify(mockWebhookData) }
});
console.log("Workflow completed:", result);
Example output
When a user sends “Hello! How are you today?” to your WhatsApp bot, it might respond with multiple messages like:
Hey there! 👋 I'm doing great, thanks for asking!
How's your day going so far?
I'm here and ready to chat about whatever's on your mind
Whether you need help with something or just want to talk, I'm all ears! 😊
What's new with you?
The bot maintains conversation context through memory and delivers responses that feel natural for WhatsApp messaging.