QXX.fi
Streaming API

Subscribe to the market in real time.

Stream normalized events milliseconds after they finalize, over gRPC or WebSocket, with server-side filters and typed SDKs — the same schema you query historically.

stream.ts
typescript
1// Subscribe to normalized market trades in real time2import { QXX } from "@qxx/stream";34const stream = new QXX({ apiKey: process.env.QXX_KEY })5  .subscribe("market.trades", {6    symbols: ["BTC-USD", "ETH-USD", "AAPL"],7    filter: "size_usd > 50000",8    delivery: "at-least-once", // deduped, ordered9  });1011for await (const trade of stream) {12  console.log(trade.ts, trade.symbol, trade.price);13}
Delivery guarantees

Real-time you can build a business on.

Freshness, ordering and durability designed for trading and production systems — not best-effort feeds.

Millisecond freshness

Events are delivered within milliseconds of the source, streamed as they happen.

Ordered per stream

Events arrive in deterministic order within each subscription.

Replay & backfill

Reconnect and resume from your last offset; missed windows backfill automatically.

Server-side filters

Filter by chain, asset, size and more before data ever leaves our edge.

gRPC & WebSocket

Binary gRPC for the lowest latency, WebSocket for reach — one schema for both.

At-least-once + dedupe

Idempotent event keys give you effectively exactly-once processing.

Latency

Where the milliseconds go.

Indicative delivery latency, measured end-to-end. Co-located deployments cut the last mile further.

Stagep50p99
Source → delivery210 ms480 ms
Stream fan-out< 5 ms< 20 ms
Reconnect + replay< 1 s< 3 s
Get started

Start streaming financial data.

Get API access to open your first subscription, or book a demo to review latency and delivery for your workload.

Usage-based pricing · Free tier · SOC 2–aligned