Welcome! We're thrilled that you're considering contributing to our [Ultralytics](https://www.ultralytics.com/) [open-source](https://github.com/ultralytics) projects. Your involvement not only helps enhance the quality of our repositories but also benefits the entire [computer vision](https://www.ultralytics.com/glossary/computer-vision-cv) community. This guide provides clear guidelines and best practices to help you get started.
To ensure a welcoming and inclusive environment for everyone, all contributors must adhere to our [Code of Conduct](https://docs.ultralytics.com/help/code-of-conduct/). **Respect**, **kindness**, and **professionalism** are at the heart of our community.
We greatly appreciate contributions in the form of [pull requests (PRs)](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/about-pull-requests). To make the review process as smooth as possible, please follow these steps:
1.**[Fork the repository](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/fork-a-repo):** Start by forking the relevant Ultralytics repository (e.g., [ultralytics/ultralytics](https://github.com/ultralytics/ultralytics)) to your GitHub account.
2.**[Create a branch](https://docs.github.com/en/desktop/making-changes-in-a-branch/managing-branches-in-github-desktop):** Create a new branch in your forked repository with a clear, descriptive name reflecting your changes (e.g., `fix-issue-123`, `add-feature-xyz`).
3.**Make your changes:** Implement your improvements or fixes. Ensure your code adheres to the project's style guidelines and doesn't introduce new errors or warnings.
4.**Test your changes:** Before submitting, test your changes locally to confirm they work as expected and don't cause [regressions](https://en.wikipedia.org/wiki/Software_regression). Add tests if you're introducing new functionality.
5.**[Commit your changes](https://docs.github.com/en/desktop/making-changes-in-a-branch/committing-and-reviewing-changes-to-your-project-in-github-desktop):** Commit your changes with concise and descriptive commit messages. If your changes address a specific issue, include the issue number (e.g., `Fix #123: Corrected calculation error.`).
6.**[Create a pull request](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request):** Submit a pull request from your branch to the `main` branch of the original Ultralytics repository. Provide a clear title and a detailed description explaining the purpose and scope of your changes.
Before we can merge your pull request, you must sign our [Contributor License Agreement (CLA)](https://docs.ultralytics.com/help/CLA/). This legal agreement ensures that your contributions are properly licensed, allowing the project to continue being distributed under the [AGPL-3.0 license](https://www.ultralytics.com/legal/agpl-3-0-software-license).
When adding new functions or classes, please include [Google-style docstrings](https://google.github.io/styleguide/pyguide.html). These docstrings provide clear, standardized documentation that helps other developers understand and maintain your code.
This example includes both a Google-style docstring and [type hints](https://docs.python.org/3/library/typing.html) for arguments and returns, though using either independently is also acceptable.
For smaller or simpler functions, a single-line docstring may be sufficient. The docstring must use three double-quotes, be a complete sentence, start with a capital letter, and end with a period.
All pull requests must pass the [GitHub Actions](https://github.com/features/actions) [Continuous Integration](https://docs.ultralytics.com/help/CI/) (CI) tests before they can be merged. These tests include linting, unit tests, and other checks to ensure that your changes meet the project's quality standards. Review the CI output and address any issues that arise.
## ✨ Best Practices for Code Contributions
When contributing code to Ultralytics projects, keep these best practices in mind:
- **Avoid code duplication:** Reuse existing code wherever possible and minimize unnecessary arguments.
- **Make smaller, focused changes:** Focus on targeted modifications rather than large-scale changes.
- **Simplify when possible:** Look for opportunities to simplify the code or remove unnecessary parts.
- **Consider compatibility:** Before making changes, consider whether they might break existing code using Ultralytics.
- **Use consistent formatting:** Tools like [Ruff Formatter](https://github.com/astral-sh/ruff) can help maintain stylistic consistency.
- **Add appropriate tests:** Include [tests](https://docs.ultralytics.com/guides/model-testing/) for new features to ensure they work as expected.
## 👀 Reviewing Pull Requests
Reviewing pull requests is another valuable way to contribute. When reviewing PRs:
- **Check for unit tests:** Verify that the PR includes tests for new features or changes.
- **Review documentation updates:** Ensure [documentation](https://docs.ultralytics.com/) is updated to reflect changes.
- **Evaluate performance impact:** Consider how changes might affect [performance](https://docs.ultralytics.com/guides/yolo-performance-metrics/).
- **Verify CI tests:** Confirm all [Continuous Integration tests](https://docs.ultralytics.com/help/CI/) are passing.
- **Provide constructive feedback:** Offer specific, clear feedback about any issues or concerns.
- **Recognize effort:** Acknowledge the author's work to maintain a positive collaborative atmosphere.
## 🐞 Reporting Bugs
We highly value bug reports as they help us improve the quality and reliability of our projects. When reporting a bug via [GitHub Issues](https://github.com/ultralytics/ultralytics/issues):
- **Check existing issues:** Search first to see if the bug has already been reported.
- **Provide a [Minimum Reproducible Example](https://docs.ultralytics.com/help/minimum-reproducible-example/):** Create a small, self-contained code snippet that consistently reproduces the issue. This is crucial for efficient debugging.
- **Describe the environment:** Specify your operating system, Python version, relevant library versions (e.g., [`torch`](https://pytorch.org/), [`ultralytics`](https://github.com/ultralytics/ultralytics)), and hardware ([CPU](https://en.wikipedia.org/wiki/Central_processing_unit)/[GPU](https://www.ultralytics.com/glossary/gpu-graphics-processing-unit)).
- **Explain expected vs. actual behavior:** Clearly state what you expected to happen and what actually occurred. Include any error messages or tracebacks.
## 📜 License
Ultralytics uses the [GNU Affero General Public License v3.0 (AGPL-3.0)](https://www.ultralytics.com/legal/agpl-3-0-software-license) for its repositories. This license promotes [openness](https://en.wikipedia.org/wiki/Openness), [transparency](https://www.ultralytics.com/glossary/transparency-in-ai), and [collaborative improvement](https://en.wikipedia.org/wiki/Collaborative_software) in software development. It ensures that all users have the freedom to use, modify, and share the software, fostering a strong community of collaboration and innovation.
We encourage all contributors to familiarize themselves with the terms of the [AGPL-3.0 license](https://opensource.org/license/agpl-v3) to contribute effectively and ethically to the Ultralytics open-source community.
Using Ultralytics YOLO models or code in your project? The [AGPL-3.0 license](https://opensource.org/license/agpl-v3) requires that your entire derivative work also be open-sourced under AGPL-3.0. This ensures modifications and larger projects built upon open-source foundations remain open.
Complying means making the **complete corresponding source code** of your project publicly available under the AGPL-3.0 license.
1.**Choose Your Starting Point:**
- **Fork Ultralytics YOLO:** Directly fork the [Ultralytics YOLO repository](https://github.com/ultralytics/ultralytics) if building closely upon it.
- **Use Ultralytics Template:** Start with the [Ultralytics template repository](https://github.com/ultralytics/template) for a clean, modular setup integrating YOLO.
│ └── model_wrapper.py # Code interacting with YOLO
├── tests/ # Unit/integration tests
├── configs/ # YAML/JSON config files
├── docker/ # Dockerfiles, if used
│ └── Dockerfile
└── .github/ # GitHub specific files (e.g., workflows for CI)
└── workflows/
└── ci.yml
```
By following these guidelines, you ensure compliance with AGPL-3.0, supporting the open-source ecosystem that enables powerful tools like Ultralytics YOLO.
Thank you for your interest in contributing to [Ultralytics](https://www.ultralytics.com/) [open-source](https://github.com/ultralytics) YOLO projects. Your participation is essential in shaping the future of our software and building a vibrant community of innovation and collaboration. Whether you're enhancing code, reporting bugs, or suggesting new features, your contributions are invaluable.
We're excited to see your ideas come to life and appreciate your commitment to advancing [object detection](https://www.ultralytics.com/glossary/object-detection) technology. Together, let's continue to grow and innovate in this exciting open-source journey. Happy coding! 🚀🌟
Contributing to Ultralytics YOLO open-source repositories improves the software, making it more robust and feature-rich for the entire community. Contributions can include code enhancements, bug fixes, documentation improvements, and new feature implementations. Additionally, contributing allows you to collaborate with other skilled developers and experts in the field, enhancing your own skills and reputation. For details on how to get started, refer to the [Contributing via Pull Requests](#-contributing-via-pull-requests) section.
To sign the Contributor License Agreement (CLA), follow the instructions provided by the CLA bot after submitting your pull request. This process ensures that your contributions are properly licensed under the AGPL-3.0 license, maintaining the legal integrity of the open-source project. Add a comment in your pull request stating:
Google-style docstrings provide clear, concise documentation for functions and classes, improving code readability and maintainability. These docstrings outline the function's purpose, arguments, and return values with specific formatting rules. When contributing to Ultralytics YOLO, following Google-style docstrings ensures that your additions are well-documented and easily understood. For examples and guidelines, visit the [Google-Style Docstrings](#-google-style-docstrings) section.
Before your pull request can be merged, it must pass all GitHub Actions Continuous Integration (CI) tests. These tests include linting, unit tests, and other checks to ensure the code meets the project's quality standards. Review the CI output and fix any issues. For detailed information on the CI process and troubleshooting tips, see the [GitHub Actions CI Tests](#-github-actions-ci-tests) section.
To report a bug, provide a clear and concise [Minimum Reproducible Example](https://docs.ultralytics.com/help/minimum-reproducible-example/) along with your bug report. This helps developers quickly identify and fix the issue. Ensure your example is minimal yet sufficient to replicate the problem. For more detailed steps on reporting bugs, refer to the [Reporting Bugs](#-reporting-bugs) section.
### What does the AGPL-3.0 license mean if I use Ultralytics YOLO in my own project?
If you use Ultralytics YOLO code or models (licensed under AGPL-3.0) in your project, the AGPL-3.0 license requires that your entire project (the derivative work) must also be licensed under AGPL-3.0 and its complete source code must be made publicly available. This ensures that the open-source nature of the software is preserved throughout its derivatives. If you cannot meet these requirements, you need to obtain an [Enterprise License](https://www.ultralytics.com/license). See the [Open-Sourcing Your Project](#-open-sourcing-your-yolo-project-under-agpl-30) section for details.