RPC method

eth_blockNumber on Sei

Supported on SwiftNodes

Everything below was measured on 2026-10-13 by calling eth_blockNumber on Sei through the same endpoint customers use, and is re-measured weekly.

What eth_blockNumber does

Returns the number of the most recent block the node has, as a hex string. It is the cheapest way to tell whether a node is keeping up and the usual starting point for polling a chain.

eth_blockNumber on Sei: what we measured

Head block when measured	237,364,964 (0xe25e6e4)
Age of that block when read	0 s
Median gap between newHeads over WebSocket	460 ms
"safe" behind the head	0 blocks
"finalized" behind the head	0 blocks

What this means for polling

Sei produces a block about every 460 ms, so a client that polls eth_blockNumber once a second sees the number jump by about 2 each time. If you need every block, subscribe to newHeads over WebSocket (see eth_subscribe on Sei) or fetch the skipped range with eth_getBlockByNumber.

"finalized" pointed at the head block itself on Sei: its nodes report each new block as finalized, so the tag adds no safety over "latest". If you need settlement on Ethereum or protection from deep reorgs, check Sei's own finality rules rather than the tag.

Compared with other chains

Measured by the gap between WebSocket headers, Sei has the 7th fastest block cadence of the 40 chains we measure.

Example request

curl -s https://rpc.swiftnodes.io/rpc/sei?key=YOUR_API_KEY \
  -X POST -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_blockNumber","params":[]}'

import { createPublicClient, http } from "viem";

const client = createPublicClient({
  transport: http("https://rpc.swiftnodes.io/rpc/sei?key=YOUR_API_KEY"),
});

const head = await client.getBlockNumber(); // bigint

// Follow the chain: poll about once per block (460 ms on Sei)
const unwatch = client.watchBlockNumber({
  pollingInterval: 460,
  onBlockNumber: (n) => console.log("new head", n),
});

Other methods on Sei

eth_chainIdSupported
eth_getBalanceSupported
eth_getBlockByNumberSupported
eth_getTransactionByHashNot measured
eth_getTransactionReceiptNot measured
eth_callSupported
eth_estimateGasSupported
eth_gasPriceSupported
eth_maxPriorityFeePerGasSupported
eth_sendRawTransactionSupported
eth_getTransactionCountNot measured
eth_getCodeSupported
eth_subscribeSupported
eth_getLogsSupported
eth_getBlockReceiptsSupported
eth_feeHistorySupported
eth_getProofNot available
eth_createAccessListSupported
debug_traceCallSupported
trace_blockNot available
trace_transactionNot available

eth_blockNumber on other chains

Frequently asked questions

Does Sei support eth_blockNumber?

Yes. eth_blockNumber answered on the SwiftNodes Sei endpoint when our weekly probe called it through the customer path (2026-10-13).

How fast are blocks on Sei?

About 460 ms per block, averaged over recent blocks (measured 2026-10-13).

How often should I poll eth_blockNumber on Sei?

Polling cannot keep up with 460 ms blocks; subscribe to newHeads over WebSocket instead.

Sei endpoints, live block height and WebSocket status are on the Sei RPC page.

One key covers every chain we serve, and SwiftNodes has a free tier.