eth_blockNumber on Core
Everything below was measured on 2026-10-13 by calling eth_blockNumber on Core 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 Core: what we measured
| Head block when measured | 39,528,226 (0x25b2722) |
|---|---|
| Age of that block when read | 3 s |
| Average block time (last 1,000 blocks) | 3.0 s |
| Median gap between newHeads over WebSocket | 3.0 s |
| "safe" behind the head | 1 blocks (about 3 s) |
| "finalized" behind the head | 2 blocks (about 6 s) |
What this means for polling
At 3.0 s per block, a one-second poll returns a new number on roughly one call in 3. Polling at the block time keeps you current without wasting requests.
"finalized" trailed the head by only 2 blocks on Core, so blocks become final almost immediately.
Compared with other chains
Measured by the gap between WebSocket headers, Core has the 36th fastest block cadence of the 40 chains we measure.
Example request
curl -s https://rpc.swiftnodes.io/rpc/core?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/core?key=YOUR_API_KEY"),
});
const head = await client.getBlockNumber(); // bigint
// Follow the chain: poll about once per block (3.0 s on Core)
const unwatch = client.watchBlockNumber({
pollingInterval: 3000,
onBlockNumber: (n) => console.log("new head", n),
});Other methods on Core
- eth_chainIdSupported
- eth_getBalanceSupported
- eth_getBlockByNumberSupported
- eth_getTransactionByHashSupported
- eth_getTransactionReceiptSupported
- eth_callSupported
- eth_estimateGasSupported
- eth_gasPriceSupported
- eth_maxPriorityFeePerGasSupported
- eth_sendRawTransactionSupported
- eth_getTransactionCountSupported
- eth_getCodeSupported
- eth_subscribeSupported
- eth_getLogsSupported
- eth_getBlockReceiptsSupported
- eth_feeHistorySupported
- eth_getProofSupported
- eth_createAccessListSupported
- debug_traceCallSupported
- trace_blockSupported
- trace_transactionNot available
eth_blockNumber on other chains
- Ethereum
- Base
- Arbitrum
- Optimism
- Polygon
- BNB Smart Chain
- Avalanche
- Sonic
- Linea
- Scroll
- zkSync Era
- Blast
- Mantle
- Gnosis
- Celo
- Berachain
- Monad
- Unichain
- Kaia
- PulseChain
- World Chain
- Ronin
- Abstract
- ApeChain
- MegaETH
- Fantom
- Lisk
- Hemi
- X Layer
- BOB
- Plasma
- Fraxtal
- Zora
- Story
- Soneium
- Sei
- Hyperliquid
- Taiko
- Morph
- Ink
- Katana
- Ethereum Classic
- opBNB
- Mode
- Flare
- Chiliz
- Telos EVM
- Tempo
- Cronos
- Manta Pacific
- Shibarium
- Boba Network
- Arbitrum Nova
- Immutable zkEVM
Frequently asked questions
Does Core support eth_blockNumber?
Yes. eth_blockNumber answered on the SwiftNodes Core endpoint when our weekly probe called it through the customer path (2026-10-13).
How fast are blocks on Core?
About 3.0 s per block, averaged over recent blocks (measured 2026-10-13).
How often should I poll eth_blockNumber on Core?
About once per block, every 3.0 s. Faster polling mostly returns the same number.
Core endpoints, live block height and WebSocket status are on the Core RPC page.
One key covers every chain we serve, and SwiftNodes has a free tier.