Kusama WebSocket RPC

Stream Kusama data in real time over a WebSocket connection instead of polling: new and finalized block headers. Every SwiftNodes plan includes a Kusama WebSocket endpoint alongside HTTP, with flat-rate pricing and no KYC.

Endpoint

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

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

Subscribe to Kusama in real time

import { ApiPromise, WsProvider } from "@polkadot/api";

const api = await ApiPromise.create({ provider: new WsProvider("wss://rpc.swiftnodes.io/ws/kusama?key=YOUR_API_KEY") });

// Stream new Kusama block headers (chain_subscribeNewHeads under the hood)
const unsub = await api.rpc.chain.subscribeNewHeads((header) =>
  console.log("new block", header.number.toNumber()),
);

What you can subscribe to

• New block headers (chain_subscribeNewHeads): the subscription our checks open on this chain
• Finalized headers (chain_subscribeFinalizedHeads)

Free keys get one WebSocket connection with new-block subscriptions only. Every other subscription listed here needs a paid plan, which also raises the connection limit.

Kusama is a Layer 0 relay chain (Substrate, nominated proof-of-stake), with ~~6 seconds block times and grandpa deterministic finality (typically within seconds) finality. That cadence sets how frequently new-block subscriptions fire.

Frequently asked questions

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