Base Sepolia RPC Endpoint

Chain ID 84532. Base's OP Stack testnet, settling to Ethereum Sepolia, with 2-second blocks like Base mainnet.

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

Endpoints

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

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

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

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

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

About Base Sepolia

Base Sepolia is the testnet for Base, Coinbase's OP Stack L2. It posts its data to Ethereum Sepolia the same way Base mainnet posts to Ethereum, so deposits, withdrawals and finality behave like mainnet at testnet prices.

Like other OP Stack chains it has three heads: latest (unsafe) blocks every 2 seconds, safe once the batch is on L1, and finalized once that L1 block is finalized. Code that waits for finalized waits much longer than on L1, which is worth testing here before mainnet.

What we measured

Measured through our endpoint on October 18, 2026.

Chain ID	84532 (0x14a34)
Block interval	2.00 s over 200 blocks
Block gas limit	1,200,000,000
Base fee	0.005 gwei
eth_maxPriorityFeePerGas	0.001 gwei
safe / finalized	49 and 471 blocks behind the head

Frequently asked questions

What is the Base Sepolia chain ID?

84532, or 0x14a34 in hex.

Is the Base Sepolia RPC endpoint free?

Yes. The free plan covers Base Sepolia at 20 requests per second and 250,000 requests a month, on the same key as Base mainnet.

How far behind is the finalized block on Base Sepolia?

When we measured, finalized was 471 blocks behind the head, about 16 minutes at 2-second blocks, and safe was 49 blocks behind.

Which L1 does Base Sepolia settle to?

Ethereum Sepolia. Bridge deposits start on Sepolia and arrive on Base Sepolia.

Other testnets

Get a free Base Sepolia endpoint

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