Build Price Alert Bot

This tutorial will guide you through building a real-time price monitoring bot from scratch that automatically sends Telegram notifications when target token price changes exceed a set threshold.

Estimated Time: 30 minutes
Difficulty Level: ⭐⭐ Beginner

Objective

Build a bot that monitors token prices and sends automatic notifications: Feature Checklist:

✅ Subscribe to real-time price stream
✅ Set price change trigger conditions (> X%)
✅ Send Telegram notifications
✅ Support multi-token monitoring

Tech Stack

Component	Technology	Purpose
Language	Node.js 18+	Main development language
Real-time Data	WebSocket	Subscribe to price stream
Notification	Telegram Bot API	Send alerts
Configuration	Environment Variables	Store sensitive info

Prerequisites

ChainStream account (to get Access Token)
Node.js 18+
Telegram Account

Step 1: Connect WebSocket

1.1 Install Dependencies

npm install @chainstream-io/sdk node-telegram-bot-api dotenv

1.2 Create Project Structure

price-alert-bot/
├── .env
├── config.js
├── bot.js
└── index.js

1.3 Configuration Files

.env:

CHAINSTREAM_ACCESS_TOKEN=your_access_token
TELEGRAM_BOT_TOKEN=your_bot_token
TELEGRAM_CHAT_ID=your_chat_id

config.js:

import 'dotenv/config';

// ChainStream Config
export const CHAINSTREAM_ACCESS_TOKEN = process.env.CHAINSTREAM_ACCESS_TOKEN;

// Telegram Config
export const TELEGRAM_BOT_TOKEN = process.env.TELEGRAM_BOT_TOKEN;
export const TELEGRAM_CHAT_ID = process.env.TELEGRAM_CHAT_ID;

// Watch Config
export const WATCH_TOKENS = [
  {
    chain: 'sol',
    address: '6p6xgHyF7AeE6TZkSmFsko444wqoP15icUSqi2jfGiPN',
    symbol: 'EXAMPLE',
    thresholdPercent: 3.0  // Trigger at 3% change
  },
  {
    chain: 'sol',
    address: 'So11111111111111111111111111111111111111112',
    symbol: 'SOL',
    thresholdPercent: 5.0  // Trigger at 5% change
  }
];

1.4 WebSocket Connection

index.js:

import { ChainStreamClient } from '@chainstream-io/sdk';
import { CHAINSTREAM_ACCESS_TOKEN, WATCH_TOKENS } from './config.js';
import { sendAlert } from './bot.js';

class PriceMonitor {
  constructor() {
    this.client = new ChainStreamClient(CHAINSTREAM_ACCESS_TOKEN);
    this.lastPrices = new Map(); // Record last prices
  }

  async start() {
    console.log('✅ Starting price monitoring...');

    // Subscribe to each token's stats
    for (const token of WATCH_TOKENS) {
      this.subscribeToken(token);
    }
  }

  subscribeToken(token) {
    this.client.stream.subscribeTokenStats({
      chain: token.chain,
      tokenAddress: token.address,
      callback: (data) => this.handlePriceUpdate(token, data)
    });

    console.log(`📡 Subscribed to ${token.symbol} price stream`);
  }

  handlePriceUpdate(token, data) {
    const currentPrice = data.price || data.p;
    if (!currentPrice) return;

    const lastPrice = this.lastPrices.get(token.address);

    if (lastPrice) {
      // Calculate change percentage
      const changePercent = ((currentPrice - lastPrice) / lastPrice) * 100;

      // Check if alert should be triggered
      if (Math.abs(changePercent) >= token.thresholdPercent) {
        this.triggerAlert(token, currentPrice, changePercent);
      }
    }

    // Update price record
    this.lastPrices.set(token.address, currentPrice);
  }

  async triggerAlert(token, price, change) {
    const direction = change > 0 ? '📈 UP' : '📉 DOWN';

    const message = `
${direction} Price Alert!

🪙 Token: ${token.symbol}
💰 Current Price: $${price.toFixed(6)}
📊 Change: ${change >= 0 ? '+' : ''}${change.toFixed(2)}%
⚡ Threshold: ${token.thresholdPercent}%
    `.trim();

    await sendAlert(message);
    console.log(`🚨 Alert sent: ${token.symbol} ${change >= 0 ? '+' : ''}${change.toFixed(2)}%`);
  }
}

// Start monitoring
const monitor = new PriceMonitor();
monitor.start();

Step 2: Set Trigger Conditions

Trigger conditions are configured in config.js:

export const WATCH_TOKENS = [
  {
    symbol: 'EXAMPLE',
    thresholdPercent: 3.0  // Trigger when price change > 3%
  },
  // ...
];

Advanced Trigger Conditions

Can be extended to more complex conditions:

// Multi-condition triggers
const ALERT_CONDITIONS = {
  priceChange: {
    enabled: true,
    thresholdPercent: 5.0
  },
  priceAbove: {
    enabled: true,
    value: 100  // Trigger when price exceeds $100
  },
  priceBelow: {
    enabled: true,
    value: 50   // Trigger when price falls below $50
  }
};

Step 3: Send Notifications

3.1 Create Telegram Bot

Create Bot

Search for @BotFather in Telegram, send /newbot

Get Token

Follow prompts to create Bot, get Bot Token

Get Chat ID

Send a message to your Bot
Visit https://api.telegram.org/bot<TOKEN>/getUpdates
Find chat.id

3.2 Telegram Notification Module

bot.js:

import TelegramBot from 'node-telegram-bot-api';
import { TELEGRAM_BOT_TOKEN, TELEGRAM_CHAT_ID } from './config.js';

const bot = new TelegramBot(TELEGRAM_BOT_TOKEN);

export async function sendAlert(message) {
  try {
    await bot.sendMessage(TELEGRAM_CHAT_ID, message, {
      parse_mode: 'HTML'
    });
  } catch (error) {
    console.error(`❌ Telegram send failed: ${error.message}`);
  }
}

export async function sendAlertWithRetry(message, maxRetries = 3) {
  for (let attempt = 0; attempt < maxRetries; attempt++) {
    try {
      await sendAlert(message);
      return true;
    } catch (error) {
      if (attempt < maxRetries - 1) {
        // Exponential backoff
        await new Promise(resolve => setTimeout(resolve, 2 ** attempt * 1000));
      } else {
        console.error(`❌ Notification failed after ${maxRetries} retries`);
        return false;
      }
    }
  }
}

Verify Installation

Run Bot

node index.js

Expected Output

✅ Starting price monitoring...
📡 Subscribed to EXAMPLE price stream
📡 Subscribed to SOL price stream

Trigger Test

Temporarily set threshold to 0.01% for quick testing:

thresholdPercent: 0.01  // For testing

Extension Suggestions

Multi-Token Monitoring
Persistent Storage
Web Dashboard
Multi-Channel Notifications

// Dynamically fetch watchlist from API
async function fetchWatchlist() {
  const response = await fetch('https://api.chainstream.io/v1/watchlist');
  return response.json();
}

import Database from 'better-sqlite3';

const db = new Database('alerts.db');

// Create table
db.exec(`
  CREATE TABLE IF NOT EXISTS alerts (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    symbol TEXT,
    price REAL,
    change REAL,
    timestamp INTEGER
  )
`);

function saveAlert(alertData) {
  const stmt = db.prepare(`
    INSERT INTO alerts (symbol, price, change, timestamp)
    VALUES (?, ?, ?, ?)
  `);
  stmt.run(
    alertData.symbol,
    alertData.price,
    alertData.change,
    Date.now()
  );
}

import express from 'express';

const app = express();

app.get('/alerts', (req, res) => {
  const alerts = getRecentAlerts();
  res.json({ alerts });
});

app.post('/config', (req, res) => {
  // Update monitoring config
  updateConfig(req.body);
  res.json({ success: true });
});

app.listen(3000);

async function sendNotification(message, channels) {
  const tasks = [];
  
  if (channels.includes('telegram')) {
    tasks.push(sendTelegram(message));
  }
  if (channels.includes('discord')) {
    tasks.push(sendDiscord(message));
  }
  if (channels.includes('email')) {
    tasks.push(sendEmail(message));
  }
  
  await Promise.all(tasks);
}

FAQ

WebSocket connection failed?

Check if Access Token is correct
Confirm network can access ChainStream
Check if firewall is blocking WebSocket

Not receiving Telegram notifications?

Confirm Bot Token is correct
Confirm Chat ID is correct
Make sure you’ve sent a message to the Bot (activate conversation)

How to monitor more tokens?

Add more configurations to the WATCH_TOKENS array in config.js.

WebSocket API

WebSocket subscription details

Webhook Fundamentals

Use Webhook instead of WebSocket

Frameworks

Tutorials

Build Price Alert Bot

Objective

Tech Stack

Prerequisites

Step 1: Connect WebSocket

1.1 Install Dependencies

1.2 Create Project Structure

1.3 Configuration Files

1.4 WebSocket Connection

Step 2: Set Trigger Conditions

Advanced Trigger Conditions

Step 3: Send Notifications

3.1 Create Telegram Bot

3.2 Telegram Notification Module

Verify Installation

Run Bot

Expected Output

Trigger Test

Extension Suggestions

FAQ

WebSocket API

Webhook Fundamentals

Frameworks

Tutorials

​Objective

​Tech Stack

​Prerequisites

​Step 1: Connect WebSocket

​1.1 Install Dependencies

​1.2 Create Project Structure

​1.3 Configuration Files

​1.4 WebSocket Connection

​Step 2: Set Trigger Conditions

​Advanced Trigger Conditions

​Step 3: Send Notifications

​3.1 Create Telegram Bot

​3.2 Telegram Notification Module

​Verify Installation

​Run Bot

​Expected Output

​Trigger Test

​Extension Suggestions

​FAQ

​Related Documentation

WebSocket API

Webhook Fundamentals

Objective

Tech Stack

Prerequisites

Step 1: Connect WebSocket

1.1 Install Dependencies

1.2 Create Project Structure

1.3 Configuration Files

1.4 WebSocket Connection

Step 2: Set Trigger Conditions

Advanced Trigger Conditions

Step 3: Send Notifications

3.1 Create Telegram Bot

3.2 Telegram Notification Module

Verify Installation

Run Bot

Expected Output

Trigger Test

Extension Suggestions

FAQ

Related Documentation