Tapedeck

Live demo

The engine, running in your browser

Twelve markets across two exchanges, three strategies, three bar clocks. Change anything and the backtest re-runs in this tab on the same deterministic kernel the command line uses. Free, no account, and nothing leaves your browser: the page replays a committed year of real exchange data locally.

loading the tape…

bars

Every change re-runs the backtest. Starting equity is 100,000 in the market's quote currency, and the defaults are the exact configuration behind the published report.

Equity hover to read a date

Drawdown hover to read a date

The address bar already holds this configuration. Anyone opening it recomputes the same numbers, with no account and nothing stored.

Open the full report for this run Trade list, cost breakdown and run settings, generated by the same function the CLI calls. The link carries the configuration, so it opens on this run and can be shared.

Four things worth trying

Where the result comes from

Set the costs to none

The result roughly quadruples. That gap is the whole argument: a backtester that skips fees reports a strategy that does not exist.

Run Bitcoin on both exchanges

Same asset, same year, same rule. On Binance the crossover ends slightly ahead; on Coinbase's entry tier it loses 24%, with fees coming to more than three times the gross profit. A result is a claim about a venue, not about a coin.

Hunt for a better period

Across a 5×5 grid of them, thirteen of nineteen lose money, and none finishes with more winners than losers.

Switch to daily bars

The same rule on the same year, sampled differently, is a different strategy. The daily candles are aggregated from the hourly tape in this tab — nothing extra is downloaded to see them.