Ethereum Sepolia RPC Endpoint

Chain ID 11155111. Ethereum's main testnet for applications and contracts, over HTTP and WebSocket on one free API key.

Online right now, checked every 2 minutes. WebSocket: available.

Endpoints

https://rpc.swiftnodes.io/rpc/eth-sepolia?key=YOUR_API_KEY
wss://rpc.swiftnodes.io/ws/eth-sepolia?key=YOUR_API_KEY

The same API key works here and on Ethereum mainnet, and testnet requests count toward your plan like any other request. The free plan includes testnets. Going to mainnet means changing eth-sepolia to eth in the URL.

import { createPublicClient, http } from "viem";
import { sepolia } from "viem/chains";

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

console.log(await client.getBlockNumber());

About Ethereum Sepolia

Sepolia is the Ethereum testnet that application developers deploy contracts to before mainnet. It runs proof of stake with a permissioned validator set, so blocks keep coming on a steady 12-second slot schedule and its ETH is only available from faucets.

Most L2 testnets, including Base Sepolia, Arbitrum Sepolia and OP Sepolia, settle to Sepolia, and Polygon Amoy checkpoints to it, which makes it the default place to test anything that crosses from L1 to L2. For staking and client testing, use Hoodi instead.

What we measured

Measured through our endpoint on October 18, 2026.

Chain ID	11155111 (0xaa36a7)
Block 1	October 23, 2021
Block interval	12.18 s average over 200 blocks
Block gas limit	200,000,000
Base fee	18 wei
eth_maxPriorityFeePerGas	2 wei
safe / finalized	61 and 93 blocks behind the head

Frequently asked questions

What is the Sepolia chain ID?

11155111, or 0xaa36a7 in hex.

Is the Sepolia RPC endpoint free?

Yes. A free SwiftNodes key works on Sepolia at 20 requests per second and 250,000 requests a month, the same limits as mainnet on the free plan. Paid plans raise both.

Should I use Sepolia or Hoodi?

Sepolia for applications and contracts; Hoodi for validators, staking and client testing. Hoodi replaced Holesky for that role in 2025.

Does Sepolia support the safe and finalized block tags?

Yes. When we measured, safe was 61 blocks and finalized 93 blocks behind the head, about two epochs, as on Ethereum mainnet.

Where do I get Sepolia ETH?

From a Sepolia faucet. Sepolia ETH has no value and cannot be bought from us; the RPC endpoint only reads the chain and broadcasts your signed transactions.

Other testnets

Get a free Ethereum Sepolia endpoint

One key for every testnet and mainnet we serve. No credit card, no KYC.

Get your API key