Lightning-fast
realtime data streams

Built on HTTP/3 (QUIC) with automatic WebSocket fallback.
Open source protocol for realtime pub/sub.

Install

pnpm add @h3channels/sdk

pnpm add @h3channels/protocol

Reliable ordered delivery over QUIC streams. Critical messages arrive intact, in order, with backpressure control.

Unreliable fast delivery for price feeds and telemetry. Client-side freshness tracking drops stale updates automatically.

UDP blocked? No problem. SDK detects unavailable WebTransport and falls back to WebSocket with the same API.

Built-in Prometheus metrics, structured logs, and OpenTelemetry hooks. Know what's happening in production.

Tick-by-tick updates for trading interfaces. Datagrams deliver price changes in microseconds. Sequence numbers prevent showing stale quotes.

System telemetry, analytics, and monitoring. Subscribe to thousands of metric channels. Redis backend scales horizontally.

Sync game state, collaborative editors, or real-time maps. Reliable streams guarantee state mutations arrive in order.

Push alerts, chat messages, and user events. Rate limiting and backpressure keep your system stable under load.

Client attempts WebTransport over QUIC. Falls back to WebSocket if UDP is blocked or unavailable.

Send a subscription request. Server opens a dedicated stream or enables datagram delivery based on your chosen mode.

Messages arrive with sequence numbers. SDK handles reconnect, resubscribe, and stale message filtering automatically.

Install the SDK and connect to your first channel in under five minutes.