# WhatsApp chat bot

This guide 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:

```bash
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.

```typescript
// 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.

```typescript
import { Agent } from '@mastra/core/agent'
import { Memory } from '@mastra/memory'
import { LibSQLStore } from '@mastra/libsql'

export const chatAgent = new Agent({
  id: 'chat-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: 'openai/gpt-5.4',
  memory: new Memory({
    storage: new LibSQLStore({
      id: 'agent-storage',
      url: 'file:../mastra.db',
    }),
  }),
})
```

## Creating the text message agent

This agent converts longer responses into natural, bite-sized text messages suitable for WhatsApp.

```typescript
import { Agent } from '@mastra/core/agent'
import { Memory } from '@mastra/memory'
import { LibSQLStore } from '@mastra/libsql'

export const textMessageAgent = new Agent({
  id: 'text-message-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: 'openai/gpt-5.4',
  memory: new Memory({
    storage: new LibSQLStore({
      id: 'agent-storage',
      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.

```typescript
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.generate([{ 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.generate([{ 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<typeof chatWorkflow>()
    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.

```typescript
import { Mastra } from '@mastra/core'
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({
    id: 'agent-storage',
    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.createRun()
          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.

```typescript
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.createRun()

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:

```text
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.