eth_getUncleByBlockNumberAndIndex

eth_getUncleByBlockNumberAndIndex returns the uncle (ommer) block header at a given index within the block at a specified height or block tag. It is the height-addressed counterpart to eth_getUncleByBlockHashAndIndex and is part of the standard eth namespace that Base — Coinbase's ETH-gas OP Stack rollup — exposes for full Ethereum tooling compatibility. On Base, blocks come from a single sequencer at roughly 2-second intervals rather than from competing miners, so the chain records no uncles. Requests to https://base.therpc.io/YOUR_API_KEY (Base mainnet, chain ID 8453 / 0x2105) consequently return null for any height and index you pass.

Use cases

• Iterate a block range by height to collect uncle headers for uncle-rate analysis on PoW networks; running the same scan across Base simply yields null at every height, confirming its zero uncle rate.
• Pass block tags such as "earliest" to reach genesis-era blocks conveniently without first looking up their hash — handy in portable tooling, though on Base the response is still null.

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_getUncleByBlockNumberAndIndex",
7    "params": [
8        "latest",
9        "0x0"
10      ],
11    "id": 1
12  }'

Try it live in the Base playground.

Errors & troubleshooting

Common pitfalls

• Base has no uncles at all — its single-sequencer OP Stack design (not proof-of-work, not multi-validator PoW) never creates ommers, so this method returns null for every block, recent or historical.
• An uncle result, where one exists on other chains, is a header only and carries no transactions array; never try to read transaction data from it.

Supported networks

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

See also

• eth_getUncleByBlockHashAndIndex
• eth_getUncleCountByBlockNumber
• eth_getBlockByNumber

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_getUncleByBlockNumberAndIndex","params":["","0x0"]}'