Optimism WebSocket RPC

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

Endpoint

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

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

Subscribe to Optimism in real time

import { createPublicClient, webSocket } from "viem";

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

// Stream new Optimism blocks as they're produced (~~2 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

Optimism is an Optimistic Rollup (OP Stack, Superchain), with ~~2 seconds block times and soft: ~2s. hard (l1): ~7 days (optimistic rollup challenge window) finality. That cadence sets how frequently new-block subscriptions fire.

Frequently asked questions

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