🔍 eth_getTransactionByBlockHashAndIndex - Base Chain JSON-RPC Method

📝 Overview

The eth_getTransactionByBlockHashAndIndex method retrieves detailed information about a transaction from the Base blockchain by specifying a block hash and the transaction's position (index) within that block.

💡 Block Explorer Alternative: This method provides programmatic access to transaction data similar to what you'd see on a block explorer, but through a direct API call to your Base node.

⚙️ Parameters

Parameter	Type	Description
`blockHash`	`String`	The 32-byte hash of the block containing the transaction
`index`	`String`	The position of the transaction in the block (hex-encoded integer)

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🔄 Returns

Transaction Object with the following fields:

Field	Type	Description
`blockHash`	`String`	32-byte hash of the block containing this transaction
`blockNumber`	`String`	Block number (hex) containing this transaction
`from`	`String`	Address of the sender
`gas`	`String`	Gas provided by the sender (hex)
`gasPrice`	`String`	Gas price provided by the sender in wei (hex)
`maxFeePerGas`	`String`	Maximum fee per gas set in the transaction (EIP-1559 only)
`maxPriorityFeePerGas`	`String`	Maximum priority fee per gas (EIP-1559 only)
`hash`	`String`	32-byte transaction hash
`input`	`String`	Data sent with the transaction
`nonce`	`String`	Number of transactions made by sender before this one (hex)
`to`	`String`	Address of the receiver (null for contract creation)
`transactionIndex`	`String`	Position of the transaction in the block (hex)
`value`	`String`	Value transferred in wei (hex)
`type`	`String`	Transaction type (0=legacy, 1=EIP-2930, 2=EIP-1559)
`accessList`	`Array`	List of addresses and storage keys the transaction plans to access
`chainId`	`String`	Chain ID of the transaction (Base mainnet is 8453)
`v`	`String`	ECDSA recovery ID
`r`	`String`	ECDSA signature r value
`s`	`String`	ECDSA signature s value

🌐 Request

POST https://base-mainnet.chainnodes.org/YOUR-API-KEY

🧪 Example

HTTPS POST Request with a JSON RPC call in the body
Replace YOUR-API-KEY with the API key from your Chainnodes.org Dashboard
You can use a different supported network by replacing base-mainnet

curl https://base-mainnet.chainnodes.org/YOUR-API-KEY \
    -X POST \
    -H "Content-Type: application/json" \
    -d '{"jsonrpc":"2.0","method":"eth_getTransactionByBlockHashAndIndex","params": ["0x54751c3cb4f7c95b249ab5ed702a708a6782cc937b1d399f25be4b40d9e0f5d4", "0x0"],"id":1}'

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📊 Response

{
   "jsonrpc": "2.0",
   "id": 1,
   "result": {
      "blockHash": "0x54751c3cb4f7c95b249ab5ed702a708a6782cc937b1d399f25be4b40d9e0f5d4",
      "blockNumber": "0x57e450",
      "from": "0xad89a377e302791fb523ffb427f3f480cad3a72c",
      "gas": "0x3362",
      "gasPrice": "0xe12c5d1dc",
      "maxFeePerGas": "0xe12c5d1dc",
      "maxPriorityFeePerGas": "0x5f5e100",
      "hash": "0xf02e0576a830ab37f2eb1c43ed3fbcaa53d84bf5ca985ae60c71f5cac27f4cc3",
      "input": "0x3593564c000000000000000000000000000000000000000000000000000000000000006000000000000000000000000000000000000000000000000000000000000000a000000000000000000000000000000000000000000000000000000000642f1f1f000000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001000000000000000000000000c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
      "nonce": "0x1",
      "to": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
      "transactionIndex": "0x0",
      "value": "0x0",
      "type": "0x2",
      "accessList": [],
      "chainId": "0x2105",
      "v": "0x0",
      "r": "0x3b4afab91edec37c0cfe9e68f2d65c4c7e9ab23d3453eaa456bdb41e5d22548f",
      "s": "0x217ad72b41a611526a45aae9392affba8114c0bd4c25e8ef7f05cda45ef5cee0"
   }
}

🚀 Use Cases

1️⃣ Block Explorer Development

Build your own Base chain block explorer or transaction tracking tool by efficiently retrieving transaction data by block position.

// Iterate through all transactions in a block
async function getAllTransactionsInBlock(blockHash) {
  const blockData = await getBlockByHash(blockHash);
  const txCount = parseInt(blockData.transactions, 16);
  
  for (let i = 0; i < txCount; i++) {
    const txIndex = '0x' + i.toString(16);
    // Get each transaction in the block
    const tx = await getTxByBlockHashAndIndex(blockHash, txIndex);
    processTx(tx);
  }
}

2️⃣ Historical Transaction Analysis

Analyze transaction patterns and activity on Base chain by examining consecutive transactions within specific blocks.

// Analyze transactions from a significant block
{"jsonrpc":"2.0","method":"eth_getTransactionByBlockHashAndIndex","params":["0x54751c3cb4f7c95b249ab5ed702a708a6782cc937b1d399f25be4b40d9e0f5d4","0x0"],"id":1}

3️⃣ Gas Price Monitoring

Track gas prices over time by analyzing transactions at regular block intervals on Base.

// Get first transaction from blocks at different heights to track gas price trends
{"jsonrpc":"2.0","method":"eth_getBlockByNumber","params":["0x57e450",false],"id":1}
// Then for each block hash:
{"jsonrpc":"2.0","method":"eth_getTransactionByBlockHashAndIndex","params":["0xBlockHash","0x0"],"id":1}

4️⃣ MEV and Front-Running Detection

Examine transaction ordering within blocks to detect potential MEV (Maximal Extractable Value) or front-running activity on Base.

// Get all transactions in a block to analyze ordering patterns
{"jsonrpc":"2.0","method":"eth_getBlockByHash","params":["0x54751c3cb4f7c95b249ab5ed702a708a6782cc937b1d399f25be4b40d9e0f5d4",false],"id":1}
// Then for suspicious blocks, examine transactions individually:
{"jsonrpc":"2.0","method":"eth_getTransactionByBlockHashAndIndex","params":["0x54751c3cb4f7c95b249ab5ed702a708a6782cc937b1d399f25be4b40d9e0f5d4","0x1"],"id":1}

5️⃣ Cross-Chain Transaction Comparison

Compare transaction structures between Ethereum mainnet and Base transactions to understand L2-specific patterns.

// Get Base chain transaction
{"jsonrpc":"2.0","method":"eth_getTransactionByBlockHashAndIndex","params":["0xBaseBlockHash","0x0"],"id":1}
// Then compare with Ethereum mainnet transaction

🔗 Related Methods

eth_getTransactionByHash - Get transaction by hash
eth_getTransactionByBlockNumberAndIndex - Get transaction by block number and index
eth_getBlockByHash - Get block information by hash

📚 Base Chain Transaction Notes

🔢 Chain ID: Base mainnet transactions have chain ID 8453 (0x2105 in hex), while Base Goerli testnet uses 84531. This is visible in the chainId field of the transaction.

🌉 L1 Data Fees: Transactions on Base include an L1 data fee component that's not found on Ethereum mainnet. This is because Base posts transaction data to Ethereum as part of its rollup design.

💨 Gas Pricing: Base has different gas dynamics than Ethereum, often with lower base fees, though the transaction structure with maxFeePerGas and maxPriorityFeePerGas remains the same.

📝 Transaction Types: Base supports the same transaction types as Ethereum mainnet: Legacy (type 0), EIP-2930 (type 1), and EIP-1559 (type 2).

eth_feeHistory eth_getTransactionByBlockNumberAndIndex