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Kwala runs event listeners continuously on all supported chains. It monitors smart contract events and triggers your workflows the moment a matching event is emitted.

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Basic event trigger

The following example demonstrates a basic event-based trigger that monitors a smart contract on Ethereum mainnet for Transfer events. Whenever tokens are transferred from the specified contract, this trigger will activate the workflow. 
trigger:
  triggerChainID: 1
  triggerSourceContract: "0x742d35Cc6e9A5f1e7A0e6FD4C8b2Bc3F5d9E1234"
  triggerSourceContractABI: '[{"anonymous":false,"inputs":[{"indexed":true,"name":"from","type":"address"},{"indexed":true,"name":"to","type":"address"},{"indexed":false,"name":"value","type":"uint256"}],"name":"Transfer","type":"event"}]'
  triggerEventName: "Transfer"

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Filtered event trigger

You can add filters to specify which events trigger your workflow. For example, the following configuration only activates when transfers come from a specific address and exceed 1 token in value: 
trigger:
  triggerChainID: 1
  triggerSourceContract: "0x742d35Cc6e9A5f1e7A0e6FD4C8b2Bc3F5d9E1234"
  triggerSourceContractABI: '[...]'
  triggerEventName: "Transfer"
  triggerEventFilter:
    from: "0xSpecificAddress..."
    value: ">1000000000000000000"  # Greater than 1 token
Some common filter operators include:
  • Exact match: "0xAddress..."
  • Greater than: ">value"
  • Less than: "<value"
  • Range: ">=value,<=value"
  • Multiple values: ["value1", "value2"]

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Accessing event data

When event listeners subscribe to your event, they can access event data using the re.event() syntax: 
APIPayload:
  sender: "re.event(0)"    # First event parameter
  amount: "re.event(1)"    # Second event parameter
The index maps to the position of values in the event signature. For example, with LowPolBalance(address,uint256), re.event(0) returns the address and re.event(1) returns the uint256 value.

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Listening to Kwala Function events

Workflows can also listen to events emitted by Kwala Functions, enabling you to chain workflows together through computed events. 
TriggerEventName: TokenTransferEvaluated(from string, to string, amount number, category string)
RepeatEvery: event
ExecuteAfter: event
This allows you to build event-driven pipelines where one function’s output triggers another workflow. For example, a function that categorizes transfers can emit events that trigger notifications or further on-chain actions. For more details, see Listen to Kwala function events.

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Use cases

The following use cases show event listeners in action as part of theiw workflows:

Cryptocurrency deposit alerts

Get notified when deposits arrive

Low balance notifier

Alert when wallet balance drops

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Next steps

Event-based triggers

Detailed trigger configuration reference

Address tracking

Monitor wallet addresses for activity