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Contract Event Monitor

Listen for smart contract events with practical filters so your team gets alerted on the exact on-chain activity that matters.

Why teams use this monitor

This is where Web3 monitoring becomes product-aware: instead of watching infrastructure only, you watch the contract behavior your users depend on.

  • Protocol teams with a known contract and one or two critical event types
  • Ops teams that need transfer, pause, ownership, or upgrade alerts
  • Teams that want a deeper follow-up after wallet or gas monitoring

Quick start in 5 minutes

  1. Start with one contract and one event signature rather than a whole ABI if you are new to on-chain events.
  2. Use indexed parameter filters to reduce noise before adding complex alert conditions.
  3. Only add manual ABI parsing when you need richer event names or decoded values.

Configuration notes

FieldWhat to know
eventsFor the event subtype, at least one event is required. Each event should map to a concrete operational question.
indexedParamsUse indexed params for address-based filtering. This is the fastest way to cut noise.
alertConditionsNumeric thresholds belong here, for example value gte a large transfer amount.
blockConfirmationsIncrease this for expensive or high-risk actions if you want fewer false positives from short reorgs.

Recommended thresholds and defaults

  • Most teams should start with 12 confirmations on mainnet and lower values on faster L2 workflows only if latency matters.
  • If you are monitoring all Transfer events without filters, the issue is usually scope rather than interval.
  • A single high-value condition is often better than many low-signal event signatures.

Ready-made examples

ERC-20 large transfer

Track large stablecoin or treasury token movements.

Setup time: 4 min

Best for

Treasury operations, market making, and reserve monitoring

  • USDC on Ethereum
  • Transfer event only
  • Alert when value >= 1,000,000 USDC base units
{
  "name": "ERC-20 large transfer",
  "contractAddress": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
  "chainId": 1,
  "rpcUrl": "https://eth.llamarpc.com",
  "contractName": "USD Coin",
  "events": [
    {
      "eventName": "Transfer",
      "eventSignature": "Transfer(address,address,uint256)",
      "alertConditions": [
        {
          "parameter": "value",
          "operator": "gte",
          "value": "1000000000000"
        }
      ]
    }
  ],
  "blockConfirmations": 12,
  "checkIntervalSeconds": 60,
  "regions": [
    "us-east"
  ],
  "monitorSubtype": "event"
}

NFT mint detector

Detect mints by watching Transfer events from the zero address.

Setup time: 4 min

Best for

NFT launches, allowlists, and supply tracking

  • ERC-721 Transfer event
  • from = 0x0000000000000000000000000000000000000000
  • Fast 60s checks
{
  "name": "NFT mint detector",
  "contractAddress": "0xBC4CA0EdA7647A8aB7C2061c2E118A18a936f13D",
  "chainId": 1,
  "rpcUrl": "https://eth.llamarpc.com",
  "contractName": "BAYC",
  "events": [
    {
      "eventName": "Transfer",
      "eventSignature": "Transfer(address,address,uint256)",
      "indexedParams": {
        "from": "0x0000000000000000000000000000000000000000"
      }
    }
  ],
  "blockConfirmations": 12,
  "checkIntervalSeconds": 60,
  "regions": [
    "us-east"
  ],
  "monitorSubtype": "event"
}

Ownership / pause / upgrade watch

Start with the operational admin events most teams care about.

Setup time: 5 min

Best for

Protocols exposing pause, upgrade, or ownership controls

  • OwnershipTransferred
  • Paused / Unpaused
  • 15 block confirmations
{
  "name": "Ownership / pause / upgrade watch",
  "contractAddress": "0x1111111254EEB25477B68fb85Ed929f73A960582",
  "chainId": 1,
  "rpcUrl": "https://eth.llamarpc.com",
  "contractName": "Admin surface",
  "events": [
    {
      "eventName": "OwnershipTransferred",
      "eventSignature": "OwnershipTransferred(address,address)"
    },
    {
      "eventName": "Paused",
      "eventSignature": "Paused(address)"
    },
    {
      "eventName": "Unpaused",
      "eventSignature": "Unpaused(address)"
    }
  ],
  "blockConfirmations": 15,
  "checkIntervalSeconds": 120,
  "regions": [
    "us-east"
  ],
  "monitorSubtype": "event"
}

Alert example

Critical contract event

Contract alert: OwnershipTransferred detected on a monitored contract.
Previous owner -> 0x0000000000000000000000000000000000000000
New owner -> 0x1234...abcd
Suggested action: verify this change was planned and pause any dependent operational workflow until confirmed.

Troubleshooting

The monitor is quiet even though the contract is active.

Verify the event signature exactly matches the emitted event and that the contract address is on the selected chain.

Too many alerts for common transfer activity.

Add indexedParams for from/to or an alertConditions threshold on value.

You pasted an ABI but cannot find the event you need.

Start manual with a single event signature, then add ABI parsing later if needed.

Next steps