Zipline-reloaded
github.com
Community-maintained fork of Quantopian's Zipline, an open-source, event-driven Python backtester for equities with the Pipeline API and pandas support.
What it is
Zipline was the backtesting engine behind Quantopian, the crowd-sourced quant platform that closed in 2020. Zipline-reloaded is the fork that Stefan Jansen, author of Machine Learning for Algorithmic Trading, has kept working with current Python and pandas versions. It is a Python library you install with pip or conda, not an app: you write an algorithm with initialize and handle_data functions, and Zipline steps through history bar by bar, fills orders, tracks the portfolio and returns results as a pandas DataFrame.
Its most distinctive part is Pipeline, an API for computing factors (moving averages, ranks, custom calculations) across a whole universe of stocks each day, which suits cross-sectional equity research. Results plug straight into matplotlib, statsmodels or scikit-learn.
You must bring your own data. Data is loaded as bundles: the default Quandl WIKI bundle stopped updating in early 2018, so for current data you ingest CSV files or write a custom bundle for your provider. The latest release at this review was 3.1.1 (July 2025), with commits into 2026. It is free under the Apache 2.0 licence, with support through GitHub issues rather than a vendor.
Key features
- Event-driven backtesting
- Simulates your algorithm bar by bar with order handling, portfolio tracking and performance statistics.
- Pipeline API
- Computes factors across many stocks each day for cross-sectional ranking and filtering, the approach Quantopian was known for.
- Data bundles
- Ingest daily or minute bars, splits and dividends from CSV files or a custom ingest function; a Nasdaq Data Link (Quandl) bundle is built in.
- PyData integration
- Inputs and results are pandas DataFrames, so analysis works with matplotlib, scipy, statsmodels and scikit-learn.
- Trading calendars
- Uses exchange calendars so sessions, holidays and early closes are simulated correctly.
- pip and conda installs
- Installable with pip install zipline-reloaded or from conda-forge, on Python 3.9 and later.
Pricing
| Plan | Price | What you get |
|---|---|---|
| Open source | $0 | Apache 2.0 licence; install with pip or conda |
The software is free. Market data is not included: you pay your own data provider if you need current or minute-level data.
Free option: Everything: the full library under the Apache 2.0 licence. Only the market data you feed it may cost money.
Checked September 25, 2026 on github.com. Prices change; confirm on the provider's site before you subscribe.
Strengths
- Free and open source with a familiar Quantopian-style API
- Pipeline makes multi-stock factor research straightforward
- Works with the standard Python data science stack
- Documented in a widely read book on machine learning for trading
Limitations
- No current data included; the built-in Quandl WIKI bundle stopped updating in early 2018
- A code library only: no graphical interface or hosted service
- Focused on equities; no built-in options backtesting
- Maintained by a small group, with support through GitHub issues only
Good fit for
- Python quants researching equity factor strategies
- Former Quantopian users who want to rerun their algorithms
- Readers of Machine Learning for Algorithmic Trading following its examples
Look elsewhere if
- Traders who want to backtest without writing code
- Options strategy backtesting
Compare
Alternatives to Zipline-reloaded
Zipline-reloaded questions
Is Zipline still maintained?
The original Quantopian repository is inactive, but the zipline-reloaded fork is maintained; its latest release at this review was 3.1.1 from July 2025.
How do I install zipline-reloaded?
Run pip install zipline-reloaded, or install it from conda-forge. It supports Python 3.9 and later.
Where does Zipline get its data?
From bundles you ingest yourself. The default Quandl WIKI bundle stopped updating in 2018, so current data has to come from CSV files or a custom bundle for your data provider.
Is Zipline free?
Yes. It is open source under the Apache 2.0 licence.
Written from Zipline-reloaded's own website and documentation. All Trading Tools lists and compares tools; it does not recommend trades or give financial advice. Sources: github.com/stefan-jansen/zipline-reloaded, zipline.ml4trading.io, zipline.ml4trading.io/bundles.html, api.github.com/repos/stefan-jansen/zipline-reloaded/releases.