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QuantConnect LEAN

Institutional-grade event-driven backtesting and live-trading engine

By QuantConnect

Live GitHub metrics

Live GitHub data · Oct 11, 2026
Stars
21,959
Stars · 7d
+114
Stars · 30d
+433
30d momentum
+2.0%
Forks
5,295
Open issues
267
Language
C#
Last push
2 days ago

Latest release v2.4.0.1 on Aug 8, 2017. Repository created Nov 28, 2014.

14.6k14.9k15.2kJun 19Oct 11
Cumulative GitHub stars, Jun 19, 2026 to Oct 11, 2026. Source: OSSInsight star history.

What it is

LEAN is the open-source engine behind QuantConnect. It runs the same algorithm code in backtests and live trading, supports equities, options, futures, FX and crypto, and routes to several brokerages. QuantConnect's cloud adds data and compute on top.

In the maintainers' words: “Lean Algorithmic Trading Engine by QuantConnect (Python, C#)”

Markets

  • US equities
  • Options
  • Futures
  • FX
  • Crypto

Tags

  • Backtesting
  • Live trading
  • C# / Python
  • Multi-asset
  • #algorithm
  • #algorithmic-trading-engine
  • #c-sharp
  • #finance
  • #forex
  • #lean-engine
  • #options
  • #python