eth_newBlockFilter

eth_newBlockFilter creates a server-side filter that tracks new block arrivals on Base — Coinbase's OP Stack rollup that uses ETH for gas — and returns a hex filter ID. You then poll that ID with eth_getFilterChanges, and each poll hands back the hashes of blocks that have appeared since your last call. Because the Base sequencer seals a block roughly every 2 seconds, polling at a similar cadence keeps you close to the chain head. Create the filter against https://base.therpc.io/YOUR_API_KEY (Base mainnet, chain ID 8453 / 0x2105); the call takes no parameters.

Use cases

• Trigger block-level processing each time a new Base block arrives — for example re-checking whether your pending transactions have been included now that the sequencer has sealed another block.
• Keep cached state fresh by invalidating balances, prices, or contract reads on every new block hash, so a dapp on Base never shows data older than the ~2s block interval.

Parameters

This method takes no parameters. Pass an empty array [].

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_newBlockFilter",
7    "params": [],
8    "id": 1
9  }'

Try it live in the Base playground.

Errors & troubleshooting

Common pitfalls

• Polling yields only block hashes, not block bodies; call eth_getBlockByHash with each hash to pull the full block, including its transactions.
• Idle filters are dropped after roughly 5 minutes; if eth_getFilterChanges raises a filter-not-found error, recreate the filter with eth_newBlockFilter and resume polling.
• A just-arrived Base block is not yet final and could in principle be reorged before settlement to Ethereum L1; wait for the finalized tag before treating block data as irreversible.

Supported networks

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

See also

• eth_getFilterChanges
• eth_uninstallFilter
• eth_newFilter
• eth_subscribe

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_newBlockFilter","params":[]}'