eth_getLogs | Cronos RPC Docs

Query event logs on Cronos. Essential for indexing DeFi protocols, NFT marketplaces, and Crypto.com ecosystem integrations on the EVM-compatible Crypto.com blockchain.

Returns an array of all logs matching a given filter object on Cronos.

Why Cronos? Build on the EVM-compatible Crypto.com blockchain with fast finality and deep Crypto.com ecosystem integration.

When to Use This Method

The eth_getLogs method serves these key scenarios for Cronos developers building DeFi and payment applications:

Index smart contract events - Track transfers, swaps, and approvals emitted by any contract on Cronos for use in indexed databases
Monitor DeFi protocol activity - Watch for liquidity changes, price updates, and position events in real time across DeFi protocols, NFT marketplaces, and Crypto.com ecosystem integrations
Build analytics pipelines - Extract on-chain event data for dashboards, reporting, and trend analysis on Cronos
Track token holder activity - Monitor whale movements and large transfers to detect significant market activity

Track all transfer events for a specific token contract within a defined block range. The Transfer event signature hash filters for exactly this event type, and you can optionally filter by sender or recipient address using indexed topics.

JavaScript

import { JsonRpcProvider } from 'ethers';

const provider = new JsonRpcProvider('https://api-cronos-mainnet-archive.n.dwellir.com/YOUR_API_KEY');
const tokenAddress = '0x5C7F8A570d578ED84E63fdFA7b1eE72dEae1AE23';
const transferTopic = '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef';

async function getRecentTransfers(fromBlock, toBlock) {
  const logs = await provider.getLogs({
    address: tokenAddress,
    fromBlock: fromBlock,
    toBlock: toBlock,
    topics: [transferTopic]
  });

  const transfers = logs.map(log => ({
    from: '0x' + log.topics[1].slice(26),
    to: '0x' + log.topics[2].slice(26),
    amount: BigInt(log.data).toString(),
    txHash: log.transactionHash
  }));

  console.log(`Found ${transfers.length} transfers`);
  return transfers;
}

const recentTransfers = await getRecentTransfers('latest', 'latest');

2. Track DEX Swap Events

Capture swap events from a DEX to analyze trading volume, price impact, and liquidity flow. Each swap emits event parameters that include the amounts and addresses involved - ideal for building price feeds and volume aggregators.

JavaScript

const provider = new JsonRpcProvider('https://api-cronos-mainnet-archive.n.dwellir.com/YOUR_API_KEY');

const SWAP_TOPIC = '0xd78ad95fa46c994b6551d0da85fc275fe613ce37657fb8d5e3d130840159d822';
const pairAddress = '0x5C7F8A570d578ED84E63fdFA7b1eE72dEae1AE23';

async function getRecentSwaps(fromBlock, toBlock) {
  const logs = await provider.getLogs({
    address: pairAddress,
    fromBlock: fromBlock,
    toBlock: toBlock,
    topics: [SWAP_TOPIC]
  });

  return logs.map(log => ({
    sender: '0x' + log.topics[1].slice(26),
    to: '0x' + log.topics[2].slice(26),
    amount0In: BigInt('0x' + log.data.slice(2, 66)).toString(),
    amount1In: BigInt('0x' + log.data.slice(66, 130)).toString(),
    amount0Out: BigInt('0x' + log.data.slice(130, 194)).toString(),
    amount1Out: BigInt('0x' + log.data.slice(194, 258)).toString(),
    txHash: log.transactionHash
  }));
}

const swaps = await getRecentSwaps('latest', 'latest');
console.log(`Found ${swaps.length} swaps`);

3. Multi-Contract Event Aggregation

Query events from multiple contracts simultaneously by passing an array of addresses. This is useful for cross-protocol analytics - aggregating lending, borrowing, and liquidation events from multiple DeFi protocols in a single query on Cronos.

JavaScript

const provider = new JsonRpcProvider('https://api-cronos-mainnet-archive.n.dwellir.com/YOUR_API_KEY');

const contracts = [
  '0xContractA...',
  '0xContractB...',
  '0xContractC...'
];

const EVENT_TOPIC = '0x...';

async function aggregateEvents(fromBlock, toBlock) {
  const logs = await provider.getLogs({
    address: contracts,
    fromBlock: fromBlock,
    toBlock: toBlock,
    topics: [EVENT_TOPIC]
  });

  const grouped = {};
  for (const log of logs) {
    const contract = log.address;
    if (!grouped[contract]) grouped[contract] = [];
    grouped[contract].push(log);
  }

  for (const [contract, events] of Object.entries(grouped)) {
    console.log(`${contract}: ${events.length} events`);
  }

  return grouped;
}

aggregateEvents('0x100000', '0x100500');

Cronos Rate Limits

Block Range Limit

On Cronos, eth_getLogs queries are subject to a maximum block range of 500 blocks. This means the difference between fromBlock and toBlock cannot exceed 500 blocks per request.

Additionally, each query can return a maximum of 10,000 log entries.

For querying larger block ranges, split your requests into smaller batches:

JavaScript

// Example: Query in 500-block batches
const BATCH_SIZE = 500;
let fromBlock = startBlock;

while (fromBlock <= endBlock) {
  const toBlock = Math.min(fromBlock + BATCH_SIZE - 1, endBlock);
  const logs = await provider.getLogs({ fromBlock, toBlock, ...filter });
  // Process logs
  fromBlock = toBlock + 1;
}

Best Practices

Limit block range to 1,000-5,000 blocks per query to avoid timeouts and rate limits on Cronos
Use topic filters for efficient log filtering: the node filters at the storage level before returning results
For high-volume monitoring, use eth_newFilter with polling instead of repeatedly calling eth_getLogs
Store the last processed block number for incremental indexing rather than re-scanning the full chain
Be aware that eth_getLogs often has stricter rate limits than other RPC methods on Cronos

Code Examples

Error Handling

Error Code	Message	Description
-32005	Query returned more than 10000 results	Reduce block range
-32602	Invalid params	Invalid filter parameters

eth_newFilter - Create a filter for logs
eth_getFilterChanges - Poll filter for new logs

eth_getLogs - Cronos RPC Method

When to Use This Method

Common Use Cases

1. Monitor ERC20 Transfer Events

2. Track DEX Swap Events

3. Multi-Contract Event Aggregation

Cronos Rate Limits

Best Practices

Code Examples

Error Handling

On this page