Cardano WebSocket API: Live Prices, Swaps, and dApp Events Without Polling
Cardano WebSocket API: Live Prices, Swaps, and dApp Events Without Polling
Polling is the tax you pay for not having a stream: request quota burned asking "anything new?", latency equal to your polling interval, and rate limits shaping your product's responsiveness. For live charts, trading interfaces, alerting, and dashboards, push beats pull.
Nexus exposes a real-time WebSocket at wss://nexus.gerowallet.io/ws/market, SockJS transport, STOMP protocol, authenticated with the same API key as the REST surface.
What you can subscribe to
Topic | What streams |
|---|---|
| All token prices, a current snapshot on subscribe, then live updates |
| One token's price, snapshot first, then updates |
| Global DEX swap events: executed swaps, cancellations, limit-order fills |
| Events for a registered dApp blueprint |
The snapshot-then-updates pattern matters in practice: your UI renders immediately with current state and then stays current, with no separate "initial load" REST call to reconcile.
How it works
import SockJS from 'sockjs-client';
import { Client } from '@stomp/stompjs';
const client = new Client({
webSocketFactory: () =>
new SockJS('https://nexus.gerowallet.io/ws/market?access_token=nxs_your_api_key_here'),
onConnect: () => {
client.subscribe('/topic/market/prices/lovelace', (msg) =>
console.log('price', JSON.parse(msg.body)),
);
client.subscribe('/topic/swaps', (msg) =>
console.log('swap', JSON.parse(msg.body)),
);
},
});
client.activate();
Authentication happens at the handshake via an access_token query parameter or a bearer header. Each delivered message counts toward your monthly message quota, and an unsubscribe control (/app/market/unsubscribe) lets you drop per-token streams you no longer need, subscribe to what you use, not everything.
What teams build with it
Trading UIs and charts update tick-by-tick from the price topics instead of hammering a REST endpoint on an interval.
Alerting and bots react to executed swaps and limit-order fills from the global swap feed as they happen.
dApp backends consume their own blueprint event stream rather than re-scanning the chain.
Dashboards stay live all day on one persistent connection instead of thousands of polls.
The streams pair naturally with the Market Data add-on: REST for history and depth, WebSocket for now.
Pricing and access
Scale ($199) and Enterprise ($499) plans include WebSocket streaming with the plan's own connection and message limits; Enterprise includes WS Unlimited. On Builder and Growth, attach a package per API key:
Package | Concurrent connections | Messages / month | Price |
|---|---|---|---|
WS Starter | 2 | 100,000 | $29/mo |
WS Pro | 10 | 2,000,000 | $59/mo |
WS Unlimited | Unlimited | Unlimited | $99/mo |
If real-time market data matters to your product, Nexus is currently the only managed way to stream it on Cardano.
Open a connection today
The 7-day Builder trial plus a WS package gets you a live stream in an afternoon. Get your key at nexus.gerowallet.io, subscribe to a price topic, and watch the updates arrive.