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CodeBull is a paper-trading platform where you practise Python and trading concepts by building strategy bots — backtest them on real-world market data and compete with your bots against other users' strategies.

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Free to use · No credit card required · No real money, ever

sma_crossover.py Python strategy 
class Strategy:
    def __init__(self):
        self.prices = {}
        self.position = {}
        self.fast_period = 10
        self.slow_period = 20

    def on_new_tick(self, symbol, price, ctx):
        if symbol not in self.prices:
            self.prices[symbol] = []
            self.position[symbol] = False
        self.prices[symbol].append(price)

        if len(self.prices[symbol]) < self.slow_period:
            return

        prices = self.prices[symbol]
        fast_sma = sum(prices[-self.fast_period:]) / self.fast_period
        slow_sma = sum(prices[-self.slow_period:]) / self.slow_period

        if fast_sma > slow_sma and not self.position[symbol]:
            ctx.place_order(symbol, "buy", 10, "market")
            self.position[symbol] = True

Backtest · 2019–2024

▲ +11.4%

Simulated equity · 142 trades

Arena

Your bot vs 3 strategies

running

Illustrative backtest on simulated money — not real performance.

How it works

Four steps, from an idea to a result you can read.

  1. 1

    Build

    Write your strategy in Python, or snap it together with visual blocks.

  2. 2

    Backtest

    Run it against real-world market data with simulated money.

  3. 3

    Analyse

    Read the report: equity curve, trades, P/L. Learn what worked.

  4. 4

    Compete

    Enter your bot in the arena against other users' strategies.

Everything you need to practise trading

Six pillars that take you from idea to insight.

Code or blocks — your choice

Write strategies in Python, or snap them together from visual blocks. Switch between the two whenever you like — both build the same bots, and the engine runs them the same way.

Backtesting on real-world data

Replay historical data and market-price snapshots drawn from real markets, with simulated money, to see how an idea would have behaved.

Portfolio reports

Equity curve, cash, every trade and the P/L behind it — so you can see exactly where a strategy won or lost.

The arena

Enter your bot in timed arenas, where it runs against other users' strategies in sandboxed simulation accounts.

Zero risk, by design

Simulated money only. No real orders are ever sent, so you can experiment freely — including with the ideas that turn out badly.

Learn by building

Guides from the blog walk through paper trading, backtesting and your first strategy bot, step by step.

Learn by building

Practical guides, all on simulated money.

Explore the CodeBull blog →

Your first strategy is waiting

Build it in Python or visual blocks, backtest it on simulated money, and read the report. It's free, and there's no money at risk.

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