> ## Documentation Index
> Fetch the complete documentation index at: https://kwala.network/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Low wallet balance notifier
> Build an automated workflow that sends Telegram alerts when a wallet balance falls below a specified threshold using Kwala
Manually tracking wallet balances in decentralized apps can mean missed alerts and failed transactions. In this guide, we'll build a low-balance notifier that automatically sends a Telegram alert when a wallet's native token balance falls below a chosen threshold using Kwala's low-code automation platform.
With Kwala, you can create event-driven workflows using simple YAML scripts, no backend servers required.
## Objective
This guide helps you set up an automation that:
* Monitors a wallet balance on the Polygon Amoy testnet.
* Emits an event when the balance is below **0.1 POL**.
* Sends an instant Telegram alert to the user.
## Prerequisites
Make sure you have:
* A MetaMask wallet connected to the Polygon Amoy Testnet and Kwala network.
* Remix IDE to deploy the Solidity smart contract.
* A Telegram bot created via [@BotFather](https://t.me/BotFather).
* Access to the [Kwala Dashboard](https://kwala.network/dashboard) to set up the workflow.
## Step 1: Build and deploy the Solidity smart contract
This Solidity contract checks user balances and emits an event when the balance drops below 0.1 POL.
Solidity smart contract:
```solidity theme={null}
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;
/// @title Native POL balance checker (Polygon)
/// @notice Emits an event if a user's native POL balance is below 0.1 POL.
contract PolNativeBalanceChecker {
// 1 POL == 1 ether in EVM units; 0.1 POL is 0.1 ether.
uint256 public constant THRESHOLD = 0.1 ether;
event LowPolBalance(address indexed user, uint256 balanceWei);
/// @notice Read-only helper to get any address's native POL balance.
function polBalanceOf(address user) public view returns (uint256) {
return user.balance; // Wei
}
/// @notice Checks `user` balance and emits LowPolBalance if below 0.1 POL.
/// @return balanceWei The user's current balance in wei.
function checkAndWarn(address user) public returns (uint256 balanceWei) {
balanceWei = user.balance;
if (balanceWei < THRESHOLD) {
emit LowPolBalance(user, balanceWei);
}
}
/// @notice Convenience for the caller; checks your own balance and may emit.
function checkMe() external returns (uint256) {
return checkAndWarn(msg.sender);
}
}
```
**How it works**
The contract compares a user's balance with the defined threshold. If the balance is below the threshold, it emits a `LowPolBalance` event: this event becomes the **trigger** for your Kwala workflow.
Deploy the contract using Remix and connect your MetaMask wallet to Polygon Amoy Testnet. You must have POL Faucet to deploy the smart contract.
After deployment, copy your deployed smart contract address from the Amoy Polygon explorer (`https://amoy.polygonscan.com/`) to inspect the contract and its transactions.
## Step 2: Configure the Telegram bot
Before building the Kwala workflow, set up your Telegram bot:
1. Open Telegram and search @BotFather.
2. Run `/newbot` to create a bot and get a bot token.
3. Use [@userinfobot](https://t.me/userinfobot) to obtain your chat ID.
Note both:
* Bot token to access the HTTP API, for example, `7754368882:AAHS4KbbOkl5rEHoBBIR8eljgwq2PARYLyY`
* Chat ID, for example, `968602918`
Use these credentials inside the workflow to send notifications later.
Test your bot token using an API tool like ReqBin or Postman with a POST request. If the token works, the test request will deliver a Telegram notification.
## Step 3: Build the workflow in Kwala
1. Navigate to your [Kwala dashboard](https://kwala.network/dashboard).
2. Select **"Create New Workflow"**.
3. Give your workflow a name. For example, `LowBalanceNotifier1`.
### Workflow configuration
**Triggers**
This is the event that activates your workflow.
* **Execute After:** Set to event: executes the action after the event is emitted.
* **Repeat Every:** `event` triggered by the event.
* **Expires:** Add an expiration timestamp. For example, `17-09-2025 16:00` in IST.
* **ParameterValue: RecurringSource Contract:** `0x1C5a23Fd1F7fEd9A5d020858BD4b93e5c93C92a8` the deployed smart contract address, available on Amoy Polygonscan.
* **Trigger Chain ID:** `80002` Polygon Amoy Testnet
* **Recurring Event Name:** `LowPolBalance(address, uint256)`
* **Event Filter:** `NA`
* **Smart contract (optional):** You can paste the Solidity code or upload the `.sol` file.
* **Recurring source contract ABI:** Automatically fetched from the deployed contract.
**Actions**
Next, configure the action - a Telegram notification that executes when the event occurs.
* **Action Name:** for example, `telegram_notifier`
* **Action Type:** `POST API CALL`
* **API Endpoint:** `https://api.telegram.org/bot/sendMessage`
* **API Payload (JSON):**
```json theme={null}
{
"chat_id": 968602918,
"text": "Low Balance! Recharge your wallet. Add 5 POL."
}
```
* **Retries Until Success:** `5`
* **Execution Mode:** `Sequential` actions run in order
This workflow listens for the `LowPolBalance` event and triggers the action whenever it's emitted.
## Step 4: Add the YAML configuration
Below is the YAML script to use for your Kwala workflow. Save and compile this code in the Kwala dashboard.
```yaml theme={null}
Name: LowBalanceNotification15
Trigger:
TriggerSourceContract: 0x1C5a23Fd1F7fEd9A5d020858BD4b93e5c93C92a8
TriggerChainID: 80002
TriggerEventName: LowPolBalance(address,uint256)
TriggerEventFilter: NA
TriggerSourceContractABI: 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
TriggerPrice: NA
RecurringSourceContract: 0x1C5a23Fd1F7fEd9A5d020858BD4b93e5c93C92a8
RecurringChainID: 80002
RecurringEventName: LowPolBalance(address,uint256)
RecurringEventFilter: NA
RecurringSourceContractABI: WwogIHsKICAgICJhbm9ueW1vdXMiOiBmYWxzZSwKICAgICJpbnB1dHMiOiBbCiAgICAgIHsKICAgICAgICAiaW5kZXhlZCI6IHRydWUsCiAgICAgICAgImludGVybmFsVHlwZSI6ICJhZGRyZXNzIiwKICAgICAgICAibmFtZSI6ICJ1c2VyIiwKICAgICAgICAidHlwZSI6ICJhZGRyZXNzIgogICAgICB9LAogICAgICB7CiAgICAgICAgImluZGV4ZWQiOiBmYWxzZSwKICAgICAgICAiaW50ZXJuYWxUeXBlIjogInVpbnQyNTYiLAogICAgICAgICJuYW1lIjogImJhbGFuY2VXZWkiLAogICAgICAgICJ0eXBlIjogInVpbnQyNTYiCiAgICAgIH0KICAgIF0sCiAgICAibmFtZSI6ICJMb3dQb2xCYWxhbmNlIiwKICAgICJ0eXBlIjogImV2ZW50IgogIH0sCiAgewogICAgImlucHV0cyI6IFtdLAogICAgIm5hbWUiOiAiVEhSRVNIT0xEIiwKICAgICJvdXRwdXRzIjogWwogICAgICB7CiAgICAgICAgImludGVybmFsVHlwZSI6ICJ1aW50MjU2IiwKICAgICAgICAibmFtZSI6ICIiLAogICAgICAgICJ0eXBlIjogInVpbnQyNTYiCiAgICAgIH0KICAgIF0sCiAgICAic3RhdGVNdXRhYmlsaXR5IjogInZpZXciLAogICAgInR5cGUiOiAiZnVuY3Rpb24iCiAgfSwKICB7CiAgICAiaW5wdXRzIjogWwogICAgICB7CiAgICAgICAgImludGVybmFsVHlwZSI6ICJhZGRyZXNzIiwKICAgICAgICAibmFtZSI6ICJ1c2VyIiwKICAgICAgICAidHlwZSI6ICJhZGRyZXNzIgogICAgICB9CiAgICBdLAogICAgIm5hbWUiOiAiY2hlY2tBbmRXYXJuIiwKICAgICJvdXRwdXRzIjogWwogICAgICB7CiAgICAgICAgImludGVybmFsVHlwZSI6ICJ1aW50MjU2IiwKICAgICAgICAibmFtZSI6ICJiYWxhbmNlV2VpIiwKICAgICAgICAidHlwZSI6ICJ1aW50MjU2IgogICAgICB9CiAgICBdLAogICAgInN0YXRlTXV0YWJpbGl0eSI6ICJub25wYXlhYmxlIiwKICAgICJ0eXBlIjogImZ1bmN0aW9uIgogIH0sCiAgewogICAgImlucHV0cyI6IFtdLAogICAgIm5hbWUiOiAiY2hlY2tNZSIsCiAgICAib3V0cHV0cyI6IFsKICAgICAgewogICAgICAgICJpbnRlcm5hbFR5cGUiOiAidWludDI1NiIsCiAgICAgICAgIm5hbWUiOiAiIiwKICAgICAgICAidHlwZSI6ICJ1aW50MjU2IgogICAgICB9CiAgICBdLAogICAgInN0YXRlTXV0YWJpbGl0eSI6ICJub25wYXlhYmxlIiwKICAgICJ0eXBlIjogImZ1bmN0aW9uIgogIH0sCiAgewogICAgImlucHV0cyI6IFsKICAgICAgewogICAgICAgICJpbnRlcm5hbFR5cGUiOiAiYWRkcmVzcyIsCiAgICAgICAgIm5hbWUiOiAidXNlciIsCiAgICAgICAgInR5cGUiOiAiYWRkcmVzcyIKICAgICAgfQogICAgXSwKICAgICJuYW1lIjogInBvbEJhbGFuY2VPZiIsCiAgICAib3V0cHV0cyI6IFsKICAgICAgewogICAgICAgICJpbnRlcm5hbFR5cGUiOiAidWludDI1NiIsCiAgICAgICAgIm5hbWUiOiAiIiwKICAgICAgICAidHlwZSI6ICJ1aW50MjU2IgogICAgICB9CiAgICBdLAogICAgInN0YXRlTXV0YWJpbGl0eSI6ICJ2aWV3IiwKICAgICJ0eXBlIjogImZ1bmN0aW9uIgogIH0KXQ==
RecurringPrice: NA
RepeatEvery: event
ExecuteAfter: event
ExpiresIn: 1789749000
Meta: NA
ActionStatusNotificationPOSTURL:
ActionStatusNotificationAPIKey: NA
Actions:
- Name: telegram_notifier
Type: post
APIEndpoint: https://api.telegram.org/bot7754368882:AAHS4KbbOkl5rEHoBBIR8eljgwq2PARYLyY/sendMessage
APIPayload:
chat_id: '968602918'
text: LOW BALANCE! Recharge your wallet. Add 5 POL
TargetContract: NA
TargetFunction: NA
TargetParams:
ChainID: NA
EncodedABI: NA
Bytecode: NA
EncodedGoContract: NA
Metadata: NA
RetriesUntilSuccess: 5
Execution:
Mode: sequential
```
After successful compilation, deploy the workflow. Activate it in Kwala and wait for the workflow status to show **claimed**.
Make sure you are in the Kwala network (not Polygon Amoy testnet) in MetaMask when creating/deploying this workflow.
## Step 5: Create a polling workflow (Optional)
You can also create a polling workflow that calls the contract on a schedule.
**Workflow name:** for example, `Polling1`
**Trigger**
* **Execute After:** `immediate` — executes the action
* **Repeat Every:** Time interval (actions repeat on a schedule)
* **Expires:** for example, `17-09-2025 16:00` in IST
* **Recurring source value configurationInterval value:** time interval you want (for example, `1` in unit `Min/hour/days`)
* **Action status Notification POST URL:** add the workflow's notification URL
**Actions**
Add the action, a smart contract call.
* **Action Name:** for example, `Polling1`
* **Action Type:** `CALL (Smart Contract)`
* **Target Function:** `function checkAndWarn(address user)`
* **Target Smart contract:** `0x1C5a23Fd1F7fEd9A5d020858BD4b93e5c93C92a8` (deployed contract address)
* **Trigger Chain ID:** `80002` (Polygon Amoy Testnet)
Request body example:
```json theme={null}
{
"chat_id": 968602918,
"text": "Low Balance! Recharge your wallet. Add 5 POL."
}
```
Provide the wallet address that has Polygon Amoy testnet faucet tokens when calling the function.
### Add the YAML configuration for polling
```yaml theme={null}
Name: Polling1
Trigger:
TriggerSourceContract: NA
TriggerChainID: NA
TriggerEventName: NA
TriggerEventFilter: NA
TriggerSourceContractABI: NA
TriggerPrice: NA
RecurringSourceContract: NA
RecurringChainID: NA
RecurringEventName: NA
RecurringEventFilter: NA
RecurringSourceContractABI: NA
RecurringPrice: NA
RepeatEvery: 1m
ExecuteAfter: immediate
ExpiresIn: 1789732800
Meta: NA
ActionStatusNotificationPOSTURL:
ActionStatusNotificationAPIKey: NA
Actions:
- Name: Polling1
Type: call
APIEndpoint: NA
APIPayload:
Message: NA
TargetContract: 0x0F0C0b9683180DF0a13Fc176aFFd92E1F7f380f0
TargetFunction: function checkAndWarn(address user)
TargetParams:
- 0x0F0C0b9683180DF0a13Fc176aFFd92E1F7f380f0
ChainID: 80002
EncodedABI: NA
Bytecode: NA
EncodedGoContract: NA
Metadata: NA
RetriesUntilSuccess: 5
Execution:
Mode: parallel
```
Save, compile, and deploy this workflow. Activate it and wait for the workflow status to show **claimed**.
## How it works
The trigger monitors the **LowPolBalance** event, and when the event fires, the workflow sends a **POST request** to your Telegram bot API endpoint with a custom message. Within seconds, you'll receive a Telegram message automatically.
The second automated Kwala workflow (polling) runs every minute after `checkAndWarn` is called in Remix; it will trigger a notification each minute. Your Telegram will display: **"LOW BALANCE! Recharge your wallet. Add 5 POL"** repeatedly, every minute. The process runs automatically with no manual checks required.
## Test the workflow
1. Ensure your wallet balance is **below 0.1 POL**.
2. In Remix, call `checkAndWarn(address user)`.
3. When the balance condition is met, the event is emitted, and Kwala's nodes detect it.
4. Kwala executes the Telegram notification instantly.
You'll receive: **"LOW BALANCE! Recharge your wallet. Add 5 POL."** every minute (as the polling workflow repeats).
## Conclusion
In this guide, you built a real-time wallet balance notifier using Kwala's low-code workflow automation. The notifier has no backend servers or infrastructure overhead; just a smart contract and a YAML configuration. Kwala empowers developers to create, automate, and scale on-chain logic effortlessly.
## Next steps
Learn how to track and analyze your workflow executions in real-time
Discover tips and patterns for building robust Web3 automations