eth_getTransactionByBlockHashAndIndex

eth_getTransactionByBlockHashAndIndex fetches a single transaction by its position inside a specific Avalanche C-Chain block, where the block is named by its hash and the transaction by its zero-based index. It returns the same transaction object as eth_getTransactionByHash — sender, recipient, AVAX value, gas fields, input data — but addressed by location rather than by transaction hash. Because a block hash pins one exact block (not a height that could be reorged away), it is the precise way to walk a known block's contents. Send the request to https://avalanche.therpc.io/YOUR_API_KEY (chain ID 43114, 0xa86a).

Use cases

• Enumerate every transaction in a known C-Chain block by walking the index from 0x0 upward until the call returns null.
• Pull the first transaction in a block to study ordering and MEV patterns in the AVAX-fee market.
• Resolve a transaction from a block-position reference (block hash plus index) when that is what your data source recorded instead of a tx hash.

Parameters

Response

Example request

1curl https://avalanche.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 Avalanche playground.

Errors & troubleshooting

Common pitfalls

• The index is hex-encoded — pass "0x0" for the first transaction, not the integer 0, or the node rejects the params.
• If the index is past the block's transaction count (or the block hash is unknown), the call returns null rather than an error, so null-check before reading fields.

Supported networks

• Mainnet — Chain ID: 43114
• Fuji

See also

• eth_getTransactionByHash
• eth_getTransactionByBlockNumberAndIndex
• eth_getBlockByHash
• eth_getTransactionReceipt

1curl https://avalanche.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"]}'