eth_getTransactionByBlockHashAndIndex

eth_getTransactionByBlockHashAndIndex returns one transaction from a Base block, located by the block's hash and the transaction's zero-based position within it. It is the positional counterpart to eth_getTransactionByHash: useful when you already hold a block hash and want to walk its transactions in order. Base is Coinbase's OP Stack optimistic rollup that settles to Ethereum L1 and uses ETH for gas, with its sequencer ordering transactions into ~2s blocks. Call it at https://base.therpc.io/YOUR_API_KEY (chain ID 8453, hex 0x2105) with a 32-byte block hash and a hex index. The reply is the full transaction object, or null if the block or index does not exist.

Use cases

• Walk every transaction in a known Base block in order by incrementing the index from 0x0 until the call returns null.
• Pull the first transaction in a block to study sequencer ordering and MEV positioning under Base's single-sequencer model.
• Resolve a transaction from a block-position reference (block hash + index) when that is what you have, instead of looking it up by transaction hash.

Parameters

Response

Example request

1curl https://base.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_getTransactionByBlockHashAndIndex",
7    "params": [
8        "0x0000000000000000000000000000000000000000000000000000000000000000",
9        "0x0"
10      ],
11    "id": 1
12  }'

Try it live in the Base playground.

Errors & troubleshooting

Common pitfalls

• The index is hex-encoded: pass "0x0" for the first transaction, not the integer 0.
• If the index is past the block's last transaction the call returns null rather than an error, so use that as your stop condition when iterating.

Supported networks

• Mainnet — Chain ID: 8453
• Sepolia — Chain ID: 84532

See also

• eth_getTransactionByHash
• eth_getTransactionByBlockNumberAndIndex
• eth_getBlockByHash
• eth_getTransactionReceipt

1curl https://base.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_getTransactionByBlockHashAndIndex","params":["0x0000000000000000000000000000000000000000000000000000000000000000","0x0"]}'