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Monitor USDC Transfer events on Ethereum mainnet to build a token tracker or analyze transfer patterns.

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Use Case

Event logs are emitted by smart contracts when specific actions occur. This example tracks all USDC Transfer events, which you can use to:
  • Build token transfer trackers
  • Analyze trading patterns
  • Monitor wallet activity
  • Track liquidity flows

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Code Example

curl --compressed -X POST "https://portal.sqd.dev/datasets/ethereum-mainnet/stream" \
  -H 'Content-Type: application/json' \
  -d '{
    "type": "evm",
    "fromBlock": 18000000,
    "toBlock": 18100000,
    "fields": {
      "block": {
        "number": true,
        "timestamp": true
      },
      "log": {
        "address": true,
        "topics": true,
        "data": true,
        "transactionHash": true,
        "logIndex": true
      }
    },
    "logs": [{
      "address": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
      "topic0": ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]
    }]
  }'

import { DataSource } from "@subsquid/portal-client";

const dataSource = new DataSource({
  network: "ethereum-mainnet",
});

// USDC contract address
const USDC_ADDRESS = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
// Transfer(address,address,uint256) event signature
const TRANSFER_TOPIC =
  "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef";

const blocks = await dataSource.getBlocks({
  from: 18000000,
  to: 18100000,
  fields: {
    block: { number: true, timestamp: true },
    log: {
      address: true,
      topics: true,
      data: true,
      transactionHash: true,
      logIndex: true,
    },
  },
  logs: [
    {
      address: [USDC_ADDRESS],
      topic0: [TRANSFER_TOPIC],
    },
  ],
});

// Process the logs
for (const block of blocks) {
  for (const log of block.logs) {
    const from = `0x${log.topics[1].slice(26)}`;
    const to = `0x${log.topics[2].slice(26)}`;

    console.log({
      blockNumber: block.header.number,
      timestamp: block.header.timestamp,
      txHash: log.transactionHash,
      from,
      to,
      // Decode amount from data field as needed
    });
  }
}

import requests
import json

url = "https://portal.sqd.dev/datasets/ethereum-mainnet/stream"
headers = {"Content-Type": "application/json"}

payload = {
    "type": "evm",
    "fromBlock": 18000000,
    "toBlock": 18100000,
    "fields": {
        "block": {
            "number": True,
            "timestamp": True
        },
        "log": {
            "address": True,
            "topics": True,
            "data": True,
            "transactionHash": True,
            "logIndex": True
        }
    },
    "logs": [{
        "address": ["0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"],
        "topic0": ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]
    }]
}

response = requests.post(url, headers=headers, json=payload)

for line in response.text.strip().split('\n'):
    block = json.loads(line)
    for log in block.get('logs', []):
        from_address = "0x" + log['topics'][1][26:]
        to_address = "0x" + log['topics'][2][26:]

        print({
            "blockNumber": block['header']['number'],
            "timestamp": block['header']['timestamp'],
            "txHash": log['transactionHash'],
            "from": from_address,
            "to": to_address
        })
Try it yourself with the interactive query interface below:

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Key Parameters

ParameterDescription
addressContract address to filter logs. Array supports multiple addresses (OR logic)
topic0Event signature (keccak256 hash of event definition). For Transfer: Transfer(address,address,uint256)
topic1First indexed parameter (from address in Transfer events)
topic2Second indexed parameter (to address in Transfer events)
topicsArray containing all event topics. topic[0] is signature, topic[1-3] are indexed params
dataNon-indexed event parameters (amount in Transfer events)
To get the event signature, compute keccak256("Transfer(address,address,uint256)"). The result is 0xddf252ad....

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Expected Output

Each line in the response represents one block containing matching logs: 
{
  "header": {
    "number": 18000123,
    "timestamp": 1697544779
  },
  "logs": [
    {
      "address": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
      "topics": [
        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
        "0x000000000000000000000000a9d1e08c7793af67e9d92fe308d5697fb81d3e43",
        "0x00000000000000000000000028c6c06298d514db089934071355e5743bf21d60"
      ],
      "data": "0x0000000000000000000000000000000000000000000000000000000002faf080",
      "transactionHash": "0x123...",
      "logIndex": 45
    }
  ]
}

​
Filtering Multiple Contracts

Query logs from multiple ERC-20 tokens: 
curl --compressed -X POST "https://portal.sqd.dev/datasets/ethereum-mainnet/stream" \
  -H 'Content-Type: application/json' \
  -d '{
    "type": "evm",
    "fromBlock": 18000000,
    "toBlock": 18010000,
    "fields": {
      "log": {
        "address": true,
        "topics": true,
        "data": true
      }
    },
    "logs": [{
      "address": [
        "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
        "0xdAC17F958D2ee523a2206206994597C13D831ec7",
        "0x6B175474E89094C44Da98b954EedeAC495271d0F"
      ],
      "topic0": ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]
    }]
  }'

const blocks = await dataSource.getBlocks({
  from: 18000000,
  to: 18010000,
  fields: {
    log: { address: true, topics: true, data: true },
  },
  logs: [
    {
      address: [
        "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48", // USDC
        "0xdAC17F958D2ee523a2206206994597C13D831ec7", // USDT
        "0x6B175474E89094C44Da98b954EedeAC495271d0F", // DAI
      ],
      topic0: [
        "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef",
      ],
    },
  ],
});

payload = {
    "type": "evm",
    "fromBlock": 18000000,
    "toBlock": 18010000,
    "fields": {
        "log": {
            "address": True,
            "topics": True,
            "data": True
        }
    },
    "logs": [{
        "address": [
            "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",  # USDC
            "0xdAC17F958D2ee523a2206206994597C13D831ec7",  # USDT
            "0x6B175474E89094C44Da98b954EedeAC495271d0F"   # DAI
        ],
        "topic0": ["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"]
    }]
}

​
Performance Tips

  1. Request only needed fields: Don’t request data if you only need addresses
  2. Use specific filters: Filter by contract address and event signature
  3. Batch appropriately: Query 10k-50k blocks at a time for best performance
  4. Filter by indexed parameters: Use topic1, topic2, topic3 to narrow results

Query Transactions

Monitor transaction activity

Track NFT Transfers

Monitor NFT collection events

Index DEX Swaps

Track DEX trading activity

API Reference

View complete API docs