Backtesting.py vs Composer (2026)
Backtesting.py (lightweight open-source python library for backtesting single-instrument strategies) and Composer (no-code platform for building, backtesting, and auto-trading rules-based strategies) solve backtesting differently. The table below compares them on verified specs and pricing; full details are in each review.
Side by side
| Backtesting.py | Composer | |
|---|---|---|
| Overall score | 7.1 / 10 | 6.2 / 10 |
| Engine type | hybrid | visual/no-code |
| Pricing model | open-source | freemium |
| Free tier | Yes | Yes |
| Entry price | $0 | $0 |
| Languages | Python | No-code visual editor, Natural language (AI strategy generation), Composer API / MCP (language-agnostic, symphonies as structured scores) |
| Asset classes | stocks, forex, crypto, futures, any instrument with OHLC(V) candlestick data | US stocks, ETFs, Crypto (state-eligible, via Alpaca Crypto), Options (covered calls & cash-secured puts, launched Dec 2025) |
| Bundled data | None beyond bundled sample datasets (GOOG daily, EURUSD intraday) used in tutorials. You bring your own OHLCV data as pandas DataFrames from yfinance, ccxt, broker APIs, or paid vendors | Bundled daily adjusted-close history for US stocks/ETFs (split/dividend adjusted) plus crypto; no separate data subscription or fees; historical depth varies by symbol and is not officially documented |
| Finest resolution | Any OHLC bar interval you supply, including sub-minute bars; raw tick or order-book data must be resampled to candles first | Daily. Backtests run on daily adjusted closing prices only; live strategies execute in a daily trade window with real-time quotes |
| Live trading | No | Yes |
| Options support | No | Yes |
| Open source | Yes | No |
Backtesting.py
Lightweight open-source Python library for backtesting single-instrument strategies
Composer
No-code platform for building, backtesting, and auto-trading rules-based strategies
Frequently asked questions
Is Backtesting.py better than Composer?+
They target different users. Backtesting.py: beginner-to-intermediate python traders who want the fastest path from strategy idea to a credible single-instrument backtest with interactive charts, without paying anything or learning a heavyweight framework. Composer: hands-off retail investors automating daily-rebalanced etf/stock rotation strategies without code. not for intraday traders or research-grade quants. Our scores: Backtesting.py 7.1/10, Composer 6.2/10.
Which is cheaper, Backtesting.py or Composer?+
Backtesting.py entry pricing: $0 (open-source). Composer: $0 (freemium). See each review for full verified pricing tables.
Educational content only, not investment advice. Specs and prices come from each platform's official pages; see the individual reviews for sources and last-verified dates.