---
title: "LEAN Engine Versions"
description: "The latest master branch on the LEAN repository is the engine branch that runs the backtesting, research, and live trading nodes in QuantConnect Cloud."
canonical: https://www.quantconnect.com/docs/v2/cloud-platform/projects/lean-engine-versions
markdown: https://www.quantconnect.com/docs/v2/cloud-platform/projects/lean-engine-versions.md
language: python
source: https://github.com/QuantConnect/Documentation/tree/master/01%20Cloud%20Platform/06%20Projects/12%20LEAN%20Engine%20Versions
modified: 2026-10-30
index: https://www.quantconnect.com/llms.txt
---

# LEAN Engine Versions

[Documentation](https://www.quantconnect.com/docs/v2.md) > [Cloud Platform](https://www.quantconnect.com/docs/v2/cloud-platform.md) > [Projects](https://www.quantconnect.com/docs/v2/cloud-platform/projects.md) > LEAN Engine Versions

> Code examples are shown in Python. Append `?lang=csharp` to this URL for the C# version of this page.

## Introduction

[Video](https://player.vimeo.com/video/696286329)

The latest master branch on the LEAN GitHub repository is the default engine branch that runs the backtesting, research, and live trading nodes in QuantConnect Cloud. The latest version of LEAN is generally the safest as it includes all bug fixes.

Trading Firm or Institution tier users concerned for stability can elect to use older or custom versions of LEAN in the IDE. These are powered by the [QuantConnect/LEAN Github Branches](https://github.com/QuantConnect/Lean/branches). We use a continuous deployment process to ship custom branches to production for trading. To create a custom version of LEAN, make a pull request to LEAN which will be reviewed by our team.

## Change Branches

Follow these steps to change the LEAN engine branch that runs your backtests and live trading algorithms:

1. [Open a project](https://www.quantconnect.com/docs/v2/cloud-platform/projects/getting-started.md#02-View-All-Projects).
2. In the Project panel, click the **LEAN Engine** field and then click a branch from the drop-down menu.
3. (Optional) Click **About Version** to display the branch description.
4. If you want to always use the master branch, select the **Always use Master Branch** check box.
5. Click **Select**.

Changing the Lean engine branch only affects the current project. If you [create a new project](https://www.quantconnect.com/docs/v2/cloud-platform/projects/getting-started.md#03-Create-Projects), the new project will use the master branch by default.

## Request New Branches

Before starting a pull-request to create a new branch, [contact us](https://www.quantconnect.com/contact) to discuss the goals of the project.