Monitor USDT (ERC-20) Wallet Balance with Etherscan and Telegram Notifications

This n8n workflow automates the process of monitoring a specific USDT (ERC-20) wallet address for balance changes using Etherscan and sending notifications to Telegram when the balance falls below a predefined threshold. This helps users stay informed about their crypto holdings without manual checks.

What it does

1. Schedules Checks: The workflow is triggered periodically (e.g., every 5 minutes) to perform regular balance checks.
2. Fetches Wallet Balance: It queries the Etherscan API to retrieve the current USDT (ERC-20) balance for a specified wallet address.
3. Sets Threshold: It defines a minimum acceptable USDT balance.
4. Compares Balance: It compares the fetched balance against the predefined threshold.
5. Sends Telegram Notification: If the wallet balance falls below the threshold, a notification message is sent to a specified Telegram chat.

Prerequisites/Requirements

• n8n Instance: A running n8n instance.
• Etherscan API Key: An API key from Etherscan (free tier is sufficient for basic monitoring).
• Telegram Bot Token: A Telegram bot token obtained from BotFather.
• Telegram Chat ID: The chat ID where the notifications should be sent.
• USDT (ERC-20) Wallet Address: The specific wallet address you want to monitor.

Setup/Usage

1. Import the workflow:

   • Copy the provided JSON code.
   • In your n8n instance, go to "Workflows" and click "New".
   • Click the "Import from JSON" button and paste the copied JSON.
   • Click "Import".

2. Configure Credentials:

   • HTTP Request (Etherscan):
     • Locate the "HTTP Request" node.
     • You will need to add your Etherscan API key to the URL or headers as required by the Etherscan API documentation. The current setup doesn't explicitly show an Etherscan API key, so you'll need to manually add it to the URL in the "URL" field, typically as a query parameter &apikey=YOUR_ETHERSCAN_API_KEY.
     • The URL for fetching ERC-20 token balance is typically structured like this: https://api.etherscan.io/api?module=account&action=tokenbalance&contractaddress=0xdac17f958d2ee523a2206206994597c13d831ec7&address={{$json.walletAddress}}&tag=latest&apikey=YOUR_ETHERSCAN_API_KEY
       • Replace 0xdac17f958d2ee523a2206206994597c13d831ec7 with the USDT (ERC-20) contract address if different (this is the standard USDT contract).
       • Replace {{$json.walletAddress}} with your actual wallet address or set it in the "Edit Fields" node.
       • Replace YOUR_ETHERSCAN_API_KEY with your Etherscan API key.
   • Telegram:
     • Locate the "Telegram" node.
     • Click on "Credential" and select "New Credential".
     • Choose "Telegram API".
     • Enter your Bot Token (obtained from BotFather).
     • Enter your Chat ID (the ID of the chat or channel where the bot should send messages).

3. Configure Workflow Parameters:

   • Cron: Adjust the schedule in the "Cron" node to your desired frequency for checking the balance.
   • Edit Fields (Set):
     • Locate the "Edit Fields" node.
     • Add a field named walletAddress and set its value to the ERC-20 wallet address you want to monitor.
     • Add a field named balanceThreshold and set its value to the minimum USDT balance you want to be notified about (e.g., 100 for 100 USDT).
   • Code:
     • Locate the "Code" node.
     • This node processes the Etherscan API response. Ensure the contractAddress and decimals are correct for USDT (ERC-20). The current code correctly uses 1000000 for 6 decimals.
   • If:
     • Locate the "If" node.
     • Ensure the condition {{ $json.balance < $json.balanceThreshold }} correctly compares the fetched balance with your set threshold.

4. Activate the Workflow:

   • Once all credentials and parameters are configured, click the "Activate" toggle in the top right corner of the n8n editor to start the workflow.