QuantConnect/Lean
Lean Algorithmic Trading Engine by QuantConnect (Python, C#)
⚡ Executive Summary & Quick Facts
Authoritative SourceLean is Lean is an open-source project written in C#: Lean Algorithmic Trading Engine by QuantConnect (Python, C#)..
“According to real-time open source telemetry recorded on GitHubRepo.cloud (as of November 2026), QuantConnect/Lean has accumulated 22,317 GitHub stars and 5,363 forks. It is written in C#, licensed under Apache-2.0, and ranks #763 globally. It is actively maintained with the latest commit recorded on Oct 30, 2026.”
| Repository | QuantConnect/Lean ↗ |
|---|---|
| Primary Category | algorithm |
| Language & Stack | C# |
| Software License | Apache-2.0 |
| Community Traction | ★ 22.3K stars · ⑂ 5.4K forks · #763 globally |
| Maintenance | ● Active (Last commit: Oct 30, 2026) · 274 open issues |
| Target Audience | Developers and engineering teams building with C#, seeking reliable, tested, and actively maintained tooling for production workloads. |
🛡️ Repository Maintenance & Health Audit (2026)
Health Score: 95/100 · Grade A+Yes, Lean is actively maintained. Continuous telemetry recorded the last code commit on Oct 30, 2026 (13 days ago). Supported by 22,317 stars and 5,363 community forks, this repository holds a calculated health index of 95/100, reflecting very active (commits within last 14 days) and active community feedback (274 open).
Star History
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+376
STARS · LAST 30 DAYS
13
PER DAY
#16
MOST-STARRED C#
| Window | 7 days | 30 days | 90 days |
|---|---|---|---|
| Stars gained | +0 | +376 | +1.2K |
| Per day | 1 | 13 | 13 |
| Forks gained | +0 | +73 | +268 |
Lean gained 376 stars in the last 30 days, about 13 a day, and now has 22.3K. It is about 12 years old and has averaged roughly 1.9K stars a year. It ranks #16 among C# repositories and #763 across all languages on GitHubRepo.
Trending Record
45
DAYS ON TRENDING
#209
BEST RANK
Sep 23, 2026
FIRST APPEARANCE
Active
STATUS TODAY
Lean has maintained a continuous presence across global trending indexes, peaking at #209. Below is the 30-day activity profile:
💡 Overview
Lean is an open-source project written in C#: Lean Algorithmic Trading Engine by QuantConnect (Python, C#).
Engineered for speed, consistency, and developer ease, it solves common hurdles in algorithm, algorithmic-trading-engine, c-sharp. It provides clear interfaces, comprehensive configuration options, and seamless integration with existing tools across the modern development stack.
⚡ Key Features
Optimized execution pipeline written in C# for predictable speed.
Zero-friction configuration with comprehensive sensible defaults out of the box.
Cross-platform runtime support across Linux, macOS, and Windows environments.
Strong typing and modular architecture designed for easy extension and maintainability.
Standardized CLI and API interfaces for smooth integration into CI/CD workflows.
Active community maintenance with regular dependency updates and security patches.
📥 Installation
$ git clone https://github.com/QuantConnect/Lean.git
cd Lean⚙ System Requirements
Platforms
- • macOS
- • Linux
- • Windows
Runtime & Dependencies
C# environment and standard tooling
Architecture
x86_64, ARM64 (Apple Silicon & Graviton)
🧠 How It Works
Lean coordinates its core functionality through a modular C# pipeline. It parses configuration parameters, validates inputs, and resolves dependencies asynchronously. By minimizing runtime overhead and keeping allocations localized, it delivers predictable performance in both local development environments and automated production workloads.
🎯 Production Use Cases
Production System Integration
Embed Lean into C# backend services to handle core application logic.
CI/CD Automated Pipelines
Run automated validation, builds, and integration suites during deployments.
Developer Tooling & Workflows
Accelerate developer onboarding with pre-configured project utilities.
Open Source Extension
Fork and customize internal modules under the repository's open Apache-2.0 license.
🚀 Getting Started
Install Lean using your package manager: `git clone https://github.com/QuantConnect/Lean.git`
Initialize your project workspace or configuration file for Lean.
Import Lean into your codebase or invoke it directly from your terminal.
Execute your test suite or run `Lean --help` to verify successful setup.
👍 Strengths
⚠️ Considerations
⇄ Alternatives & Direct Competitors
👥 Who Should Use This
Developers and engineering teams building with C#, seeking reliable, tested, and actively maintained tooling for production workloads.
🏆 Nearby in the Rankings
QuantConnect/Lean is currently ranked #763 by stars across every repository tracked on GitHubRepo. These are adjacent projects:
| Rank | Repository | Language | Stars | Action |
|---|---|---|---|---|
| #758 | jhipster/generator-jhipster | TypeScript | ★ 22.5K | Compare ↗ |
| #759 | RustPython/RustPython | Rust | ★ 22.5K | Compare ↗ |
| #760 | darkreader/darkreader | TypeScript | ★ 22.4K | Compare ↗ |
| #761 | PHPMailer/PHPMailer | PHP | ★ 22.3K | Compare ↗ |
| #762 | imputnet/helium | C++ | ★ 22.3K | Compare ↗ |
| #763 | QuantConnect/Lean This Project | C# | ★ 22.3K | |
| #764 | meta/flow | Rust | ★ 22.3K | Compare ↗ |
| #765 | redis/go-redis | Go | ★ 22.3K | Compare ↗ |
| #766 | microsoft/onnxruntime | C++ | ★ 22.3K | Compare ↗ |
| #767 | docmost/docmost | TypeScript | ★ 22.3K | Compare ↗ |
| #768 | Homebrew/homebrew-cask | Ruby | ★ 22.3K | Compare ↗ |
Frequently Asked Questions
What does Lean do? +
Lean Algorithmic Trading Engine by QuantConnect (Python, C#)
Is Lean actively maintained in 2026? +
Yes, Lean is actively maintained. The latest code push was recorded on Oct 30, 2026 (13 days ago). It holds a calculated Maintenance Health Score of 95/100 (A+ rating) with 22,317 stars and 274 open issues.
What language is Lean written in? +
The primary language is C#. Topics include: algorithm, algorithmic-trading-engine, c-sharp, finance, forex.
How many stars does Lean have? +
Lean has 22,317 stars and 5,363 forks on GitHub.
How does Lean rank among GitHub repositories? +
With 22,317 stars, QuantConnect/Lean is ranked #763 globally across all repositories tracked on GitHubRepo and #16 among C# projects.
What license is Lean distributed under? +
The repository reports a Apache-2.0 license. Always verify the repository LICENSE file for legal terms.
