Backtesting vs Paper Trading vs Live
Published Jul 26, 2026
Backtesting, paper trading, and live trading validate different things: a backtest replays past market data to check whether a strategy’s logic ever worked; paper trading runs the strategy on live market data with simulated money to check that it behaves today; live trading executes with real funds through your exchange API keys and is the only stage that proves real fills, fees, and funding. On Alphafox all three run the same strategy parameters, so you can promote one strategy through the pipeline instead of rebuilding it per stage.
What each stage validates
| Stage | Market data | Money | Validates | Can’t catch |
|---|---|---|---|---|
| Backtest | Historical replay | None | Strategy logic, parameter ranges, past drawdown | Today’s regime, real fills, order-book depth |
| Paper trading | Live, real order books | Simulated (engine-managed) | Signal timing, behavior in current markets | Real slippage at your size, your fee tier, funding paid |
| Live | Live | Real, on your exchange | Everything, at your actual size | Nothing—but mistakes now cost money |
A strong backtest with no paper run is untested in the present; a good paper run with no backtest has no evidence across market phases. Use both, in that order.
The promotion pipeline
Backtest first
Describe the strategy in chat, run a backtest over months of history—no code needed. Reject anything whose drawdown you couldn’t sit through.
Paper trade the survivor
Deploy the same parameters to a paper trader. It trades real market prices with an engine-managed simulated balance—no exchange account required. Run it for weeks, across different market conditions, not days.
Go live small
Connect an exchange with trade-only API keys and start below your target size. Scale only after live behavior matches paper. Full checklist: From Paper to Live.
Why the numbers still differ
Even a perfect pipeline shows gaps between stages: backtests fill idealistically, paper matches live books but skips your real fee tier, live pays true slippage and funding. That’s environment difference, not a bug—see Paper, Backtest, and Live Differences for the comparison tables and when a gap is a real problem.
Paper runs bill at 0.01 USDT per hour versus 0.07 for live, so validating on paper first is also the cheap option. Public strategies on the leaderboard show ROI from real runs in both modes, labeled paper or live.