rx-trader : reactive, event-sourced crypto trading engine
rx-trader is a thought experiment: what happens when you model an entire crypto trading system as reactive streams?
It’s an event-sourced, RxJS-powered trading engine built with Bun and TypeScript. The core idea is that every stage of the trading pipeline — from tick ingestion to order execution — is an observable composition. Business logic stays pure; side effects live at the edges. One process, one event loop, zero microservice sprawl.
The Experiment
The hypothesis: reactive streams are a natural fit for trading systems. Ticks are streams. Signals are derived streams. Risk filters are operators. Execution is a subscriber. The same code can run backtests, paper trading, and live trading by swapping dependencies at the edges.
feeds.ticks$
-> strategies.signals$
-> intentBuilder(signals$, marks$)
-> riskFilter.check(intents$)
-> execution.submit(approved$)
-> execution.fills$
-> portfolio.snapshots$Everything is an event. Every event is persisted. Every view is a replay.
Architecture
The system splits into two data planes:
Hot path (RxJS observables) handles the trading-critical flow. Ticks stream through strategies, intent shaping, risk filters, and execution as direct observable chains. Sub-millisecond latency, compile-time type safety, backpressure control via operators like throttle, buffer, and sample.
Cold path (EventBus) handles observability. Every significant state transition is emitted as a domain event for persistence, dashboard updates, and the audit trail. Heavy I/O stays off the hot path entirely.
Packages
- core — Domain types (Zod schemas), event definitions, time abstractions
- feeds — WebSocket adapters (Binance, Hyperliquid), sentiment feed
- strategies — Strategy registry, DSL operators (rolling stats, z-scores, crossovers, cooldowns)
- risk — Pre-trade and post-trade risk modules
- execution — Paper adapter, REST venue gateways, retry/circuit breaker policy
- pipeline — Feed manager, strategy orchestrator, execution manager, intent reconciliation
- portfolio — Position/PnL analytics, balance sync, accounting