eth_getUncleCountByBlockHash

eth_getUncleCountByBlockHash returns the number of uncle blocks referenced by the block identified by a given hash, encoded as a hex string. Base — Coinbase's OP Stack optimistic rollup that pays gas in ETH — implements this standard eth-namespace method so Ethereum tooling runs without modification. In practice the answer on Base is always 0x0: blocks are sealed by a single sequencer roughly every 2 seconds, so no competing blocks become uncles. Send the request to https://base.therpc.io/YOUR_API_KEY (Base mainnet, chain ID 8453 / 0x2105) and you will get 0x0 for every valid block hash.

Use cases

• Check whether a block has any uncles before spending calls on eth_getUncleByBlockHashAndIndex; on Base the count is always 0x0, so the follow-up call is never needed.
• Build a historical uncle-rate time-series for network-health research across chains; including Base in such a study documents a flat zero line, reflecting its single-sequencer block production.

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_getUncleCountByBlockHash",
7    "params": ["0x0000000000000000000000000000000000000000000000000000000000000000"],
8    "id": 1
9  }'

Try it live in the Base playground.

Errors & troubleshooting

Common pitfalls

• On Base every block returns 0x0 because its OP Stack sequencer produces no uncles; this method is only meaningful for historical proof-of-work data on other chains, not for Base activity.
• An unknown or non-existent block hash returns null rather than 0x0, so distinguish "block has zero uncles" from "block not found" when parsing the response.

Supported networks

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

See also

• eth_getUncleByBlockHashAndIndex
• eth_getUncleCountByBlockNumber
• eth_getBlockByHash

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_getUncleCountByBlockHash","params":["0x0000000000000000000000000000000000000000000000000000000000000000"]}'