In a good product, paper and live trading look effortless: pick a mode, hit go, watch it run. That simplicity is the whole point, and it’s also a magic trick. Behind the button is a fair amount of machinery, and it’s worth seeing, because if you build your own you’ll be building exactly this.
What “just run it” actually requires
A live or paper run is a long-lived program reacting to a live market in real time. To make that work, something has to:
- Stream real-time data and feed it to your strategy in order, handling gaps and late prints.
- Keep a long-running process alive for hours, surviving the quiet stretches and the busy opens.
- Route orders to a broker (real) or a simulator (paper) and track each one through its lifecycle.
- Maintain state (positions, ledger, buying power) and, in live, reconcile it against a broker that’s the real source of truth.
- Capture everything: orders, fills, issues, and logs, so the run is inspectable, not a black box.
- Run somewhere that stays up, scales, isolates one strategy from another, and cleans up when a run ends.
- Be stoppable, with a kill that actually halts the thing.
None of that is the strategy. All of it has to exist before the strategy can trade a single share for real.
Why it’s easy to underestimate
Because the backtest hides it. A backtest needs none of this, no real-time feed, no long-lived process, no broker, no monitoring. So the leap from “my backtest works” to “let me paper/live trade it” feels small, and it isn’t. You’re not adding a feature; you’re adding an entire operational layer.
The point
This machinery is real, it’s necessary, and it’s mostly undifferentiated. It looks roughly the same for everyone who builds it well. Which makes it a strange place to spend your time. Your edge is in the strategy; the data streaming, process supervision, order tracking, and run hosting are table stakes.
So the honest question isn’t whether this infrastructure is impressive. It’s whether you want to build and run it, or have it run for you so the button really is just a button.