Query Event Logs

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

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

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:

Key Parameters

Parameter	Description
`address`	Contract address to filter logs. Array supports multiple addresses (OR logic)
`topic0`	Event signature (keccak256 hash of event definition). For Transfer: `Transfer(address,address,uint256)`
`topic1`	First indexed parameter (from address in Transfer events)
`topic2`	Second indexed parameter (to address in Transfer events)
`topics`	Array containing all event topics. topic[0] is signature, topic[1-3] are indexed params
`data`	Non-indexed event parameters (amount in Transfer events)

To get the event signature, compute keccak256("Transfer(address,address,uint256)"). The result is 0xddf252ad....

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

Request only needed fields: Don’t request data if you only need addresses
Use specific filters: Filter by contract address and event signature
Batch appropriately: Query 10k-50k blocks at a time for best performance
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

Overview

Portal API reference

Working with Portal API

Local Setup

Supported Networks

Use Case

Code Example

Key Parameters

Expected Output

Filtering Multiple Contracts

Performance Tips

Query Transactions

Track NFT Transfers

Index DEX Swaps

API Reference

​Use Case

​Code Example

​Key Parameters

​Expected Output

​Filtering Multiple Contracts

​Performance Tips

​Related Examples

Query Transactions

Track NFT Transfers

Index DEX Swaps

API Reference

Use Case

Code Example

Key Parameters

Expected Output

Filtering Multiple Contracts

Performance Tips

Related Examples