Monitoring treasury deposits and token transfers in real time is critical for DAOs, DeFi projects, and teams that manage on-chain funds. Traditionally, that requires backend servers and cron jobs: infrastructure you must maintain and secure.
Kwala Workflows removes that operational burden. With a simple YAML-driven workflow, you can listen for on-chain events and send notifications to off-chain endpoints like Discord, no backend required.
In this guide, we’ll build a real-time deposit alert system that sends a Discord notification whenever a stablecoin (USDC) is deposited into a Treasury Vault contract. The entire flow is driven by Kwala workflows and a single YAML configuration.
Objective
Create a Kwala workflow that:
- TRIGGER: Detects
USDCAccepted events emitted by the Treasury Vault contract when a USDC deposit happens.
- ACTION: Instantly posts a notification to a Discord channel via webhook.
This eliminates the need for manual monitoring or custom backend scripts for token-transfer tracking.
Prepare your Discord webhook
- Open Discord and go to Server Settings > Apps > Create New App
- Select Create a Bot and configure the name, avatar, and permissions
- Go to Server Settings > Integrations > Webhooks
- Select New Webhook, choose your target channel, then select Copy Webhook URL
- (Optional) Test the webhook with a POST request:
{"content": "Test message from Discord Webhook!"}
Keep the webhook URL handy — you’ll add it to the workflow action.
Step 1: Smart contract setup
This use case uses two Solidity contracts: a simple ERC20 (USDC-like) and a treasury vault that accepts deposits and emits an event.
MintERC20USDC.sol
Contract Address (Base Sepolia): 0x025B55313ac120435963f571F02EcC3d35FA6e6e
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
/// @title Simple USDC-like ERC20 (standalone)
/// @notice Minimal ERC20 token with mint/burn and an owner-only function to transfer tokens held by the contract.
contract USDC {
// ERC20 basic data
string public name = "USD Coin";
string public symbol = "USDC";
uint8 public constant decimals = 6; // USDC uses 6 decimals
uint256 public totalSupply;
// Owner
address public owner;
// Balances and allowances
mapping(address => uint256) public balanceOf;
mapping(address => mapping(address => uint256)) public allowance;
// Events
event Transfer(address indexed from, address indexed to, uint256 value);
event Approval(address indexed ownerAddr, address indexed spender, uint256 value);
event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);
event Mint(address indexed to, uint256 amount);
event Burn(address indexed from, uint256 amount);
// Modifiers
modifier onlyOwner() {
require(msg.sender == owner, "only owner");
_;
}
// Constructor sets deployer as owner
constructor() {
owner = msg.sender;
emit OwnershipTransferred(address(0), owner);
}
// ---------- ERC20 standard functions ----------
function transfer(address to, uint256 amount) external returns (bool) {
_transfer(msg.sender, to, amount);
return true;
}
function approve(address spender, uint256 amount) external returns (bool) {
allowance[msg.sender][spender] = amount;
emit Approval(msg.sender, spender, amount);
return true;
}
function transferFrom(address from, address to, uint256 amount) external returns (bool) {
uint256 allowed = allowance[from][msg.sender];
require(allowed >= amount, "allowance too low");
// deduct allowance
allowance[from][msg.sender] = allowed - amount;
_transfer(from, to, amount);
return true;
}
// ---------- Internal transfer ----------
function _transfer(address from, address to, uint256 amount) internal {
require(to != address(0), "transfer to zero");
uint256 bal = balanceOf[from];
require(bal >= amount, "insufficient balance");
balanceOf[from] = bal - amount;
balanceOf[to] += amount;
emit Transfer(from, to, amount);
}
// ---------- Mint / Burn (owner) ----------
/// @notice Mint tokens to an address (owner only)
function mint(address to, uint256 amount) external onlyOwner returns (bool) {
require(to != address(0), "mint to zero");
totalSupply += amount;
balanceOf[to] += amount;
emit Mint(to, amount);
emit Transfer(address(0), to, amount);
return true;
}
/// @notice Burn tokens from owner's balance
function burn(uint256 amount) external onlyOwner returns (bool) {
uint256 bal = balanceOf[owner];
require(bal >= amount, "insufficient owner balance");
balanceOf[owner] = bal - amount;
totalSupply -= amount;
emit Burn(owner, amount);
emit Transfer(owner, address(0), amount);
return true;
}
/// @notice Burn tokens from any account (owner only)
function burnFrom(address account, uint256 amount) external onlyOwner returns (bool) {
require(account != address(0), "burn from zero");
uint256 bal = balanceOf[account];
require(bal >= amount, "insufficient balance");
balanceOf[account] = bal - amount;
totalSupply -= amount;
emit Burn(account, amount);
emit Transfer(account, address(0), amount);
return true;
}
// ---------- Contract-held tokens forwarding ----------
/// @notice Transfer tokens that this contract currently holds to `to` (owner only).
/// Useful if the contract receives tokens and owner wants to forward them to their wallet.
function transferFromContract(address to, uint256 amount) external onlyOwner returns (bool) {
require(to != address(0), "to zero");
uint256 bal = balanceOf[address(this)];
require(bal >= amount, "insufficient contract balance");
balanceOf[address(this)] = bal - amount;
balanceOf[to] += amount;
emit Transfer(address(this), to, amount);
return true;
}
// ---------- Ownership ----------
function transferOwnership(address newOwner) external onlyOwner {
require(newOwner != address(0), "new owner zero");
emit OwnershipTransferred(owner, newOwner);
owner = newOwner;
}
// ---------- Allow contract to receive ETH (optional) ----------
receive() external payable { }
}
0x60Fc086C786e8B66aeD0163A266bd3aF9125e8D0
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
/// @title USDCVaultSimple
/// @notice Accepts USDC, records who sent how much, and emits an event for every deposit.
contract USDCVaultSimple {
address public usdc; // USDC token contract address
uint256 public totalReceived;
struct Deposit {
address sender;
uint256 amount;
uint256 timestamp;
}
Deposit[] public deposits;
mapping(address => uint256) public totalReceivedBy;
event USDCAccepted(address indexed sender, uint256 amount, uint256 timestamp);
constructor(address _usdc) {
require(_usdc != address(0), "Invalid USDC address");
usdc = _usdc;
}
/// @notice Deposit USDC into this contract.
/// @dev Caller must first approve this contract to spend their USDC.
function deposit(uint256 amount) external {
require(amount > 0, "Amount must be > 0");
// Call USDC.transferFrom(msg.sender, thisContract, amount)
(bool success, bytes memory data) = usdc.call(
abi.encodeWithSignature("transferFrom(address,address,uint256)", msg.sender, address(this), amount)
);
require(success && (data.length == 0 || abi.decode(data, (bool))), "Transfer failed");
deposits.push(Deposit(msg.sender, amount, block.timestamp));
totalReceived += amount;
totalReceivedBy[msg.sender] += amount;
emit USDCAccepted(msg.sender, amount, block.timestamp);
}
/// @notice Returns how many deposits have been made.
function depositsCount() external view returns (uint256) {
return deposits.length;
}
/// @notice Returns a deposit record.
function getDeposit(uint256 index) external view returns (address, uint256, uint256) {
require(index < deposits.length, "Invalid index");
Deposit memory d = deposits[index];
return (d.sender, d.amount, d.timestamp);
}
/// @notice Returns current USDC balance held by this contract.
function contractBalance() external view returns (uint256) {
(bool success, bytes memory data) = usdc.staticcall(
abi.encodeWithSignature("balanceOf(address)", address(this))
);
require(success, "balanceOf failed");
return abi.decode(data, (uint256));
}
}
- Mint USDC tokens from
MintERC20USDC.
- Approve the
TreasuryAcceptUSDC contract to spend tokens.
- Deposit tokens into the treasury (calls
deposit).
TreasuryAcceptUSDC emits USDCAccepted, which Kwala detects and uses to send a Discord alert.
Step 2: Build the Kwala workflow
Step 2.1: Create a new workflow
- Open the Kwala Dashboard: Kwala Dashboard
- Select Create New Workflow
- Name it, for example:
USDC_Received_Notifier1
- Execute After: immediately
- Repeat Every: event
- Recurring Source Contract:
0x60Fc086C786e8B66aeD0163A266bd3aF9125e8D0 (Treasury contract on Base Sepolia)
- Recurring Chain ID:
84532 (Base Sepolia testnet)
- Recurring Event Name:
USDCAccepted(address,uint256,uint256)
- Expires: An expiration date such as
08-10-2025 15:00 IST
- Action Status Notification POST URL:
This ensures every USDC deposit triggers the workflow.
- Action Name:
discord_call
- Type:
POST (API CALL)
- API Endpoint: your Discord webhook URL (example provided in the YAML)
- API Payload:
content: "USDC Received on USDC Treasury Vault Smart Contract"
- Retries Until Success:
5
- Execution Mode:
sequential
YAML: Use as-is in the Kwala dashboard
Name: USDC_Received_Notifier1_e81e
Trigger:
TriggerSourceContract: NA
TriggerChainID: NA
TriggerEventName: NA
TriggerEventFilter: NA
TriggerSourceContractABI: NA
TriggerPrice: NA
RecurringSourceContract: 0x60Fc086C786e8B66aeD0163A266bd3aF9125e8D0
RecurringChainID: 84532
RecurringEventName: USDCAccepted(address,uint256,uint256)
RecurringEventFilter: NA
RecurringSourceContractABI: 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
RecurringPrice: NA
RepeatEvery: event
ExecuteAfter: immediate
ExpiresIn: 1759915800
Meta: NA
ActionStatusNotificationPOSTURL:
ActionStatusNotificationAPIKey: NA
Actions:
- Name: discord_call
Type: post
APIEndpoint: https://discord.com/api/webhooks/1425037499574517760/wh9zok5wxXMI-rdVK-4atTZM-14eHghibVwbQN7erqs1iSME7keWQGulSZ6NNBVyaXA1
APIPayload:
content: "USDC Received on USDC Treasury Vault Smart Contract"
TargetContract: NA
TargetFunction: NA
TargetParams: NA
ChainID: NA
EncodedABI: NA
Bytecode: NA
Metadata: NA
RetriesUntilSuccess: 5
Execution:
Mode: sequential
Paste this YAML into the Kwala dashboard, save & compile, then deploy.
Step 3: Deploy and test
- Save and compile the YAML workflow in Kwala.
- Deploy it and wait for status: claimed.
- In Remix:
- Mint USDC via
MintERC20USDC (if needed).
- Approve the treasury contract to spend your USDC.
- Call
deposit(amount) on TreasuryAcceptUSDC.
- After the deposit transaction completes, the contract emits
USDCAccepted, Kwala detects it and your Discord webhook receives the message:
Discord output:
USDC Received on USDC Treasury Vault Smart Contract
Conclusion
You’ve built a real-time stablecoin deposit alert using Kwala Workflows, a single YAML workflow that connects on-chain USDCAccepted events to a Discord notification. No servers, no cron jobs, and no custom backend.
Kwala helps you connect on-chain events to off-chain systems quickly, automate DeFi treasury monitoring without operational overhead, and build event-driven Web3 infrastructure using YAML.
Next steps
