eth_getTransactionByBlockNumberAndIndex

eth_getTransactionByBlockNumberAndIndex returns a single transaction by its position inside an Avalanche C-Chain block, where the block is named by a height (hex) or a tag like latest or pending, and the transaction by its zero-based index. The payload is the same transaction object as eth_getTransactionByHash — sender, recipient, AVAX value, gas fields, input — but addressed by block-and-position rather than by hash. With the C-Chain producing blocks every 1–2 seconds under Snowman consensus, this is handy for sequential height-based scans. Send the request to https://avalanche.therpc.io/YOUR_API_KEY (chain ID 43114, 0xa86a).

Use cases

• Iterate height-by-height over the first transaction in each C-Chain block for MEV and ordering research without resolving block hashes first.
• Inspect a specific position in the next block by passing the pending tag to peek at queued mempool transactions.
• Run sequential block scans when you already have block numbers and do not need hash resolution, letting you stream the fast C-Chain by incrementing height.

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_getTransactionByBlockNumberAndIndex",
7    "params": [
8        "latest",
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.
• The pending tag's behavior (which transactions appear and in what order) depends on the node client, so treat pending results as a best-effort snapshot, not a settled C-Chain block.

Supported networks

• Mainnet — Chain ID: 43114
• Fuji

See also

• eth_getTransactionByBlockHashAndIndex
• eth_getTransactionByHash
• eth_getBlockByNumber

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_getTransactionByBlockNumberAndIndex","params":["",""]}'