Ethereum WebSocket RPC

Stream Ethereum data in real time over a WebSocket connection — new blocks, pending transactions, and contract events — instead of polling. Every SwiftNodes plan includes a Ethereum WebSocket endpoint alongside HTTP, with flat-rate pricing and no KYC.

Endpoint

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

The HTTP endpoint for Ethereum is https://rpc.swiftnodes.io/rpc/eth?key=YOUR_API_KEY. One API key works for both, and across all 75+ supported chains.

Subscribe to Ethereum in real time

import { createPublicClient, webSocket } from "viem";

const client = createPublicClient({
  transport: webSocket("wss://rpc.swiftnodes.io/ws/eth?key=YOUR_API_KEY"),
});

// Stream new Ethereum blocks as they're produced (~~12 seconds apart)
const unwatch = client.watchBlocks({
  onBlock: (block) => console.log("new block", block.number),
});

What you can subscribe to

• New block headers (newHeads) — react the moment a block lands
• Pending transactions (newPendingTransactions) — watch the mempool
• Contract event logs (logs) — filter by address and topics

Ethereum is a Layer 1 (proof-of-stake), with ~~12 seconds block times and ~12 minutes (two epochs) finality. That cadence sets how frequently new-block subscriptions fire.

Frequently asked questions

See the full Ethereum RPC page for chain details, or the WebSocket docs for the complete method list.